User equipment and base station

ABSTRACT

A User Equipment (UE) configured for multi-group communications is described. The UE includes a processor and instructions stored in memory that is in electronic communication with the processor. The UE detects a plurality of cells. The UE also determines to use multiple groups of one or more cells. The UE further determines a primary secondary cell (PSCell) for a non-primary cell (non-PCell) group based on UE-specific radio resource control (RRC) signaling. The UE additionally receives information using the multiple groups.

RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.14/846,420 entitled “IMPROVING MULTI-GROUP COMMUNICATION USING MULTIPLECHANNELS OR CELLS,” filed Sep. 4, 2015, which is a continuation of U.S.patent application Ser. No. 14/454,456 entitled “DEVICES FOR MULTI-GROUPCOMMUNICATIONS,” filed Aug. 7, 2014, now issued as U.S. Pat. No.9,148,906, which is a divisional of U.S. patent application Ser. No.13/083,456 entitled “DEVICES FOR MULTI-GROUP COMMUNICATIONS,” filed Apr.8, 2011, now issued as U.S. Pat. No. 8,837,304, which are all herebyincorporated herein by reference in their entirety.

TECHNICAL FIELD

The present disclosure relates generally to communication systems. Morespecifically, the present disclosure relates to devices for multi-groupcommunications.

BACKGROUND

Wireless communication devices have become smaller and more powerful inorder to meet consumer needs and to improve portability and convenience.Consumers have become dependent upon wireless communication devices andhave come to expect reliable service, expanded areas of coverage, andincreased functionality. A wireless communication system may providecommunication for a number of wireless communication devices, each ofwhich may be serviced by a base station. A base station may be a fixedstation that communicates with wireless communication devices.

As wireless communication devices have advanced, improvements incommunication capacity, speed and/or quality have been sought. However,improvements in communication capacity, speed and/or quality may requireincreased resources.

For example, wireless communication devices may communicate with one ormore devices using multiple channels or cells. However, communicatingwith one or more devices using multiple channels or cells may posecertain challenges. As illustrated by this discussion, systems andmethods that enable or improve communication using multiple channels orcells may be beneficial.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram illustrating one configuration of a userequipment (UE) and one or more evolved Node Bs (eNBs) in which systemsand methods for multi-group communications may be implemented;

FIG. 2 is a flow diagram illustrating one configuration of a method forperforming multi-group communications on a user equipment (UE);

FIG. 3 is a block diagram illustrating one configuration of a userequipment (UE) multi-group operation module that may be used inaccordance with the systems and methods disclosed herein;

FIG. 4 is a flow diagram illustrating a more specific configuration of amethod for performing multi-group communications on a user equipment(UE);

FIG. 5 is a block diagram illustrating another configuration of a userequipment (UE) multi-group operation module that may be used inaccordance with the systems and methods disclosed herein;

FIG. 6 is a flow diagram illustrating one configuration of a method forperforming multi-group communications on an evolved Node B (eNB);

FIG. 7 is a block diagram illustrating one configuration of an evolvedNode B (eNB) group operations module that may be used to enablemulti-group communications on an eNB;

FIG. 8 is a diagram illustrating one example of uplink transmissiontiming;

FIG. 9 is a diagram illustrating another example of uplink transmissiontiming;

FIG. 10 is a block diagram illustrating one example of a deploymentscenario;

FIG. 11 is a block diagram illustrating another example of a deploymentscenario;

FIG. 12 is a diagram illustrating one example of uplink transmissiontiming with multiple cell groups;

FIG. 13 is a diagram illustrating one example of uplink transmissiontiming adjustments in random access responses;

FIG. 14 is a diagram illustrating one example of uplink transmissiontiming adjustments from timing advance command media access control(MAC) control elements;

FIG. 15 is a diagram illustrating one example of common space monitoringin multiple groups;

FIG. 16 illustrates various components that may be utilized in a userequipment (UE); and

FIG. 17 illustrates various components that may be utilized in anevolved Node B (eNB).

DETAILED DESCRIPTION

A User Equipment (UE) configured for multi-group communications isdisclosed. The UE includes a processor and instructions stored in memorythat is in electronic communication with the processor. The UE detects aplurality of cells. The UE also determines to use multiple groups of oneor more cells. The UE further determines a primary secondary cell(PSCell) for a non-primary cell (non-PCell) group based on UE-specificradio resource control (RRC) signaling. The UE additionally receivesinformation using the multiple groups. Determining the PSCell based onRRC signaling may include receiving a message that explicitly identifiesthe PSCell. Determining the PSCell based on RRC signaling may includedetermining the PSCell based on an SCell with a random access channel(RACH), an SCell with a lowest order in a group configuration or areference cell for uplink timing.

The UE may also configure a physical uplink control channel (PUCCH) forone or more non-PCell groups. The UE may additionally determine whetherto adjust timing for the non-PCell group and use a timing advancecommand to adjust the timing for the non-PCell group if it is determinedto adjust timing for the non-PCell group.

The UE may further determine whether a path loss parameter is receivedthat designates a reference cell in the non-PCell group. Furthermore,the UE may determine a path loss based on the reference cell if the pathloss parameter is received that designates a reference cell in thenon-PCell group and transmit a path loss indicator for the non-PCellgroup if the path loss parameter is received that designates a referencecell in the non-PCell group.

The UE may also transmit information indicating a multiple uplink timealignment capability. The UE may additionally monitor a common searchspace for each group. The UE may further transmit an acknowledgement ornegative acknowledgement (ACK/NACK) for the non-PCell group.

An evolved Node B (eNB) configured for multi-group communications isalso disclosed. The eNB includes a processor and instructions stored inmemory that is in electronic communication with the processor. The eNBtransmits radio resource control (RRC) signaling indicating a primarysecondary cell (PSCell) for a non-primary cell (PCell) group. The eNBalso transmits information using the non-PCell group.

The eNB may also allocate a physical uplink control channel (PUCCH) forone or more non-PCell groups. The eNB may additionally receiveinformation indicating a user equipment (UE) multiple uplink timealignment capability. The eNB may also determine whether to adjusttiming for the non-PCell group and transmit a timing advance command forthe non-PCell group if it is determined to adjust timing for thenon-PCell group. The eNB may also transmit a path loss parameter for oneor more non-PCell groups and receive a path loss indicator. The eNB mayadditionally receive one or more acknowledgements or negativeacknowledgements (ACK/NACKs) on the PSCell.

The RRC signaling indicating the PSCell may include a message thatexplicitly identifies the PSCell. The RRC signaling may indicate thePSCell based on one selected from the group consisting of an SCell witha random access channel (RACH), an SCell with a lowest order in a groupconfiguration and an SCell that is a reference cell for uplink timing.

A method for multi-group communications on a User Equipment (UE) is alsodisclosed. The method includes detecting a plurality of cells. Themethod also includes determining to use multiple groups of one or morecells. The method additionally includes determining a primary secondarycell (PSCell) for a non-primary cell (non-PCell) group based onUE-specific radio resource control (RRC) signaling. The method furtherincludes receiving information using the multiple groups.

A method for multi-group communications on an evolved Node B (eNB) isalso disclosed. The method includes transmitting radio resource control(RRC) signaling indicating a primary secondary cell (PSCell) for anon-primary cell (PCell) group. The method also includes transmittinginformation using the non-PCell group.

The 3rd Generation Partnership Project, also referred to as “3GPP,” is acollaboration agreement that aims to define globally applicabletechnical specifications and technical reports for third and fourthgeneration wireless communication systems. The 3GPP may definespecifications for next generation mobile networks, systems, anddevices.

3GPP Long Term Evolution (LTE) is the name given to a project to improvethe Universal Mobile Telecommunications System (UMTS) mobile phone ordevice standard to cope with future requirements. In one aspect, UMTShas been modified to provide support and specification for the EvolvedUniversal Terrestrial Radio Access (E-UTRA) and Evolved UniversalTerrestrial Radio Access Network (E-UTRAN).

At least some aspects of the systems and methods disclosed herein may bedescribed in relation to the 3GPP LTE and LTE-Advanced (LTE-A) standards(e.g., Release-8 and Release-10). However, the scope of the presentdisclosure should not be limited in this regard. At least some aspectsof the systems and methods disclosed herein may be utilized in othertypes of wireless communication systems.

A wireless communication device may be an electronic device used tocommunicate voice and/or data to a base station, which in turn maycommunicate with a network of devices (e.g., public switched telephonenetwork (PSTN), the Internet, etc.). In describing systems and methodsherein, a wireless communication device may alternatively be referred toas a mobile station, a User Equipment (UE), an access terminal, asubscriber station, a mobile terminal, a remote station, a userterminal, a terminal, a subscriber unit, a mobile device, etc. Examplesof wireless communication devices include cellular phones, smart phones,personal digital assistants (PDAs), laptop computers, netbooks,e-readers, wireless modems, etc. In 3GPP specifications, a wirelesscommunication device is typically referred to as a User Equipment (UE).However, as the scope of the present disclosure should not be limited tothe 3GPP standards, the terms “UE” and “wireless communication device”may be used interchangeably herein to mean the more general term“wireless communication device.”

In 3GPP specifications, a base station is typically referred to as aNode B, an evolved or enhanced Node B (eNB), a home enhanced or evolvedNode B (HeNB) or some other similar terminology. As the scope of thedisclosure should not be limited to 3GPP standards, the terms “basestation,” “Node B,” “eNB,” and “HeNB” may be used interchangeably hereinto mean the more general term “base station.” Furthermore, the term“base station” may be used to denote an access point. An access pointmay be an electronic device that provides access to a network (e.g.,Local Area Network (LAN), the Internet, etc.) for wireless communicationdevices. The term “communication device” may be used to denote both awireless communication device and/or a base station.

The term “synchronized” and variations thereof may be used herein todenote a situation where two or more events occur in overlapping timeframes. In other words, two “synchronized” events may overlap in time tosome extent, but are not necessarily of the same duration. Furthermore,synchronized events may or may not begin or end at the same time.

It should be noted that as used herein, a “cell” may be anycommunication channel that is specified by standardization or regulatorybodies to be used for International Mobile Telecommunications-Advanced(IMT-Advanced) and all of it or a subset of it may be adopted by 3GPP aslicensed bands to be used for communication between a Node B (e.g.,eNodeB) and a UE. “Configured cells” are those cells of which the UE isaware and is allowed by Node B (e.g., eNB) to transmit or receiveinformation. “Configured cell(s)” may be serving cell(s). The UE mayreceive system information and perform the required measurements on allconfigured cells. “Activated cells” are those configured cells on whichthe UE is transmitting and receiving. That is, activated cells are thosecells for which the UE monitors the PDCCH and in the case of a downlinktransmission, those cells for which the UE decodes a Physical DownlinkShared Channel (PDSCH). “Deactivated cells” are those configured cellsthat the UE is not monitoring the transmission PDCCH.

The systems and methods disclosed herein may relate to how a userequipment (UE) behaves in case that the UE is configured for multipletiming alignment groups or multiple random access channels. In 3GPP LTERelease-10 (e.g., LTE-A or Advanced E-UTRAN), carrier aggregation isintroduced. Furthermore, a primary cell (PCell) and one or moresecondary cells (SCells) may be used.

If carrier aggregation is configured, a user equipment (UE) may havemultiple serving cells: a primary cell (PCell) and one or more secondarycells (SCell). From a network perspective, the same serving cell may beused as the primary cell (PCell) by one user equipment (UE) and used asa secondary cell (SCell) by another user equipment (UE). A primary cell(PCell) that is operating according to Release-8 or Release-9 may beequivalent to the Release-8 or Release-9 serving cell. When operatingaccording to Release-10, there may be one or more secondary cells(SCell) in addition to the primary cell (PCell) if carrier aggregationis configured.

When carrier aggregation is configured, a user equipment (UE) may haveonly one Radio Resource Control (RRC) connection with the network. Atthe RRC connection establishment, re-establishment and/or handover, oneserving cell (e.g., the primary cell (PCell)) may provide the non-accessstratum (NAS) mobility information (e.g., Tracking Area Identity (TAI))and the security input.

In the downlink, the carrier corresponding to the primary cell (PCell)is the downlink primary component carrier (DL PCC). In the uplink, thecarrier corresponding to the primary cell (PCell) is the uplink primarycomponent carrier (UL PCC). Depending on the capabilities of the userequipment (UE), one or more secondary component carriers (SCC) orsecondary cells (SCell) may be configured to form a set of serving cellswith the primary cell (PCell). In the downlink, the carriercorresponding to the secondary cell (SCell) is the downlink secondarycomponent carrier (DL SCC). In the uplink, the carrier corresponding tothe secondary cell (SCell) is the uplink secondary component carrier (ULSCC). The number of downlink component carriers may be different fromthe number of uplink component carriers because multiple cells may shareone uplink component carrier.

The UE may adjust its uplink transmission timing for a physical uplinkcontrol channel (PUCCH), physical uplink shared channel (PUSCH) and/orsounding reference signal (SRS) of the primary cell based on a timingadvance command. The timing advance command in a random access responsemay be transmitted from an eNB to a UE after the UE has sent a randomaccess preamble. The timing advance command (which refers to a timingadvance command media access control (MAC) control element) is alsotransmitted from the eNB to the UE at any time the eNB wants to changethe UE's uplink transmission timing. The uplink transmission timing mayneed to be adjusted from time to time to account for changes in theradio frequency (RF) delay as the relative position of the UE changes inrespect to a corresponding eNB. In this manner, the eNB may provide thatall signals from any UEs to the eNB reach the eNB at the same time orwithin a cyclic prefix in an orthogonal frequency division multiplexing(OFDM) symbol.

In the case of a random access response, an 11-bit timing advancecommand T_(A) may indicate N_(TA) values by index values of T_(A)=0, 1,2, K, 1282, where an amount of the time alignment is given byN_(TA)=T_(A)×16.

In other cases, a six-bit timing advance command T_(A) may indicateadjustment of a current N_(TA) value (denoted N_(TA,old)) to a newN_(TA) value (denoted N_(TA,new)) by index values of T_(A)=0, 1, 2, K,63, where N_(TA,new)=N_(TA,old)+(T_(A)−31)×16. In this case, adjustmentof an N_(TA) value by a positive or a negative amount indicatesadvancing or delaying the uplink transmission timing by a given amount,respectively.

Transmission of an uplink radio frame number i from the UE startsN_(TA)×T_(s) seconds before the start of a corresponding downlink radioframe at the UE, where 0≤N_(TA)≤20512 and

$T_{s} = \frac{1}{( {15000 \times 2048} )}$seconds. In other words, a UE may begin transmitting an uplink radioframe i N_(TA)×T_(s) seconds before receiving a corresponding downlinkradio frame i.

Typically, the uplink (UL) transmission timing for a physical uplinkshared channel (PUSCH) and/or sounding reference signal (SRS) of asecondary cell may be the same as that of a primary cell. However,aggregation between cells may be introduced with different transmissionand/or reception sites. In this case, a UE may need to have differentuplink transmission timing for each cell.

In Release-11, this multiple uplink transmission timing adjustment isinvestigated. One example of a deployment scenario is that differentcomponent carriers could see substantially different propagationenvironments due to different frequency selective repeaters and hencesee different time-of-flights. Another example deployment scenario isthat the UE may communicate with two non-collocated sites on twocarriers. Such a scenario could occur with remote antennas or remoteradio heads.

Some approaches indicate that this issue can be solved by havingmultiple time alignment groups, though the detail of operation ofmultiple time alignment groups has not been described. However, if a UEhas multiple transmission timing adjustments and the timing differenceis relatively large, problems may occur with subframe timing and crosscarrier scheduling, etc. For example, a physical uplink control channel(PUCCH) transmission or physical downlink control channel (PDCCH)transmission may not occur in time to prepare for data transmission.

One or more of the following aspects may be used in accordance with thesystems and methods disclosed herein. In addition to a group of one ormore serving cells (including a primary cell (PCell)), one or moregroups that include at least one secondary cell (SCell) are introduced.The uplink transmissions corresponding to one or more serving cells ineach group may have the same uplink transmission timing.

Each group may have one specific cell that is used as an uplink timingreference. In a group including the PCell, this specific cell may be thePCell. In a group that does not include the PCell, this specific cellmay be a specific SCell referred to as a primary SCell (PSCell) or asecondary PCell (SPCell). In the specification and claims herein, theterm “PSCell” is used to refer to a primary SCell (PSCell), a secondaryPCell (SPCell) or both. The PSCell may have intermediate featuresbetween the PCell and the SCell.

PCell features may include the following. The PCell may be used as ananchor cell of Security and Mobility. The UE may be required to performRadio Link Monitoring in the PCell. The PCell may be used as a path lossreference to other cell(s). The PCell may be used as an uplink timingreference to other cell(s). The PCell uplink timing may refer to thePCell downlink timing. The PCell may always be activated and neverdeactivated. The PCell may not be cross-carrier scheduled. The UE mayacquire System Information and/or Paging transmitted from an eNB in thePCell. The UE may monitor a Random Access Response and/or physicaldownlink control channel (PDCCH) ordered random access channel (RACH)and/or Contention Resolution for random access in the PCell. The UE maybe assigned a Semi-Persistent Scheduling resource in the PCell by theeNB. The UE may use a physical random access channel (PRACH) resource inthe PCell. The UE may use a physical uplink control channel (PUCCH)resource in the PCell.

SCell features may include the following. The SCell may not be used asan anchor cell of Security and Mobility. The UE may not be required toperform Radio Link Monitoring in the SCell. The SCell may not be used asa path loss reference to other cell(s). The SCell may not be used as anuplink timing reference to other cell(s). The SCell may be activated ordeactivated. The SCell may be cross-carrier scheduled. The UE may notacquire System Information and/or Paging transmitted from an eNB in theSCell. The UE may not monitor a Random Access Response and/or PDCCHordered RACH and/or Contention Resolution for random access in theSCell. The UE may not be assigned a Semi-Persistent Scheduling resourcein the SCell by the eNB. The UE may not be assigned a PRACH resource inthe SCell. The UE may not be assigned a PUCCH resource in the SCell.

PSCell features may include one or more of the following, for example.The PSCell may not be used as an anchor cell of Security and Mobility.The UE may be required to perform Radio Link Monitoring in the PSCell.The PSCell may be used as a path loss reference to other cell(s) withinits own group. The PSCell may be used as an uplink timing reference toother cell(s) within its own group. The PSCell uplink timing may referto the PSCell downlink timing. The PCell may always be activated and maynever be deactivated. The PSCell may not be cross-carrier scheduled. TheUE may not acquire System Information and/or Paging transmitted from aneNB in the PSCell. The UE may monitor a Random Access Response and/orPDCCH ordered RACH and/or Contention Resolution for random access in thePSCell. The UE may not be assigned a Semi-Persistent Scheduling resourcein the PSCell by an eNB. The UE may use a PRACH resource in the PSCell.The UE may use a PUCCH resource in the PSCell.

The uplink transmission timing for a PUSCH and/or SRS of an SCell ineach group may be the same as the PCell in the same group or that of thePSCell in the same group. A PSCell may have a common search space inaddition to a common search space in PCell.

A PSCell may not be cross-carrier scheduled. This means that other cellsmay not schedule a PSCell. On the other hand, a PSCell may scheduleother cells.

A PSCell may be indicated by UE-specific explicit or implicit radioresource control (RRC) signaling. In one example of implicit signaling,an SCell that is configured with a random access channel may be thePSCell.

In the case that an SCell belongs to a group that does not include thePCell, a pathlossReference-r10(pCell, sCell) parameter may be replacedby a pathlossReference-r11(psCell, sCell) parameter. A PSCell may have aPUCCH in addition to a PUCCH corresponding to the PCell. A hybridautomatic repeat request acknowledgement (HARQ-ACK) corresponding tocells in a group may be transmitted on the PSCell in the group.

More detail regarding various aspects of the systems and methodsdisclosed herein is given hereafter. In addition to a group of one ormore serving cells that includes a primary cell (PCell)), one or moregroups that include at least one secondary cell (SCell) are introduced.The uplink transmissions corresponding to one or more serving cells ineach group may have the same uplink transmission timing.

Each group may have one specific cell that is used as an uplink timingreference. In a group including the PCell, this specific cell may be thePCell. In a group that does not include the PCell, this specific cellmay be a specific SCell referred to as a primary SCell or PSCell.

The uplink transmission timing for a PUSCH and/or SRS of an SCell ineach group may be the same as the uplink transmission timing for acorresponding PCell (that is in the same group, for example) or may bethe same as the uplink transmission timing for a corresponding PSCell(that is in the same group, for example). This may be aligned with amultiple serving cell concept, which is that each serving cell has adownlink and may optionally have an uplink. Furthermore, each servingdownlink carrier and uplink carrier may belong to one serving cell.

Uplink transmission timing may need to be adjusted since all signalsfrom one or more UEs may need to reach the eNB at the same time orwithin a cyclic prefix in an OFDM symbol. In 3GPP Release-10, a UE usesthe same transmission timing for all serving cells. In that case, thereis no need to distinguish which cell or group of cells that the timingadvance command corresponds to since there is only one group foraligning uplink transmission timing.

A timing advance command in a random access response may be transmittedfrom an eNB to a UE in a PCell or in a PSCell after the UE has sent arandom access preamble in the PCell or the PSCell. This random accessresponse may be scheduled by a PDCCH including a random access radionetwork temporary identifier (RA-RNTI), which is an identifier used forscheduling a PDSCH including a random access response.

Which PCell or SCell that a received random access response is for maybe distinguished by which serving cell the random access response isscheduled in. For example, a UE may determine which cell (e.g., PCell,SCell, etc.) corresponds to a received random access response bydetermining which serving cell the random access response is scheduledin. A serving cell that the random access response is scheduled in maybe determined by identifying a cell that has a HARQ entity, a PDCCH or aPDSCH for a random access response. The random access response scheduledin a PCell downlink (DL) may be used for an uplink (UL) transmissiontiming adjustment for a PCell uplink. The random access responsescheduled in a PSCell downlink (DL) may be used for an uplink (UL)transmission timing adjustment for a PSCell uplink. It should also benoted that PDCCH detection to order a random access in a PSCell from aneNB to a UE may be in the PSCell and Contention resolution for a randomaccess in a PSCell may be in the PSCell.

Another timing advance command (e.g., a timing advance command mediaaccess control (MAC) control element) may also be transmitted from theeNB to the UE at any time the eNB wants to change the UE's uplinktransmission timing. Whether the received timing advance command is forthe PCell or for a PSCell may be distinguished based on which servingcell the timing advance command is scheduled in. A serving cell that thetiming advance command is scheduled in may be determined by identifyinga cell that has a HARQ entity, a PDCCH or a PDSCH for a timing advancecommand. It should be noted that a timing advance command MAC controlelement (which may be transmitted from an eNB at any time) is differentfrom a random access response. A timing advance command scheduled in anyserving cell in a group that includes the PCell downlink may be used foran uplink transmission timing adjustment for the PCell uplink. A timingadvance command scheduled in any serving cell(s) in the group thatincludes the PSCell downlink may be used for an uplink transmissiontiming adjustment for the PSCell uplink.

In another configuration, the timing advance command MAC control elementor a MAC header of the timing advance command MAC control element mayindicate which group the command corresponds to. A group indication maybe a cell index of a PSCell that is included in the corresponding group.

Typically, there is only one common search space in a PCell and there isno common search space in an SCell. A UE may monitor a set of PDCCHcandidates for control information on one or more activated servingcells as configured by higher layer signaling. More than one servingcell may be configured by RRC signaling and a serving cell may beactivated or deactivated by MAC signaling.

The set of PDCCH candidates to monitor may be defined in terms of searchspaces. There is a common search space on the primary cell and aUE-specific search space on the primary cell and/or the secondary cell.The common search space may be cell specific and only on the primarycell. The UE-specific search space may be defined by a cell radionetwork temporary identifier or C-RNTI (e.g., user equipment identifier(UEID)) and may be prepared for each serving cell.

Different kinds of information or data may be transmitted in the commonsearch space. For example, a PDCCH to schedule system information orpaging information, random access related information or normal UE datamay be transmitted in the common search space. The physical layer of aUE may be configured by higher layers with a RNTI. The UE may decode thePDCCH with a cyclic redundancy check (CRC) scrambled by the RNTI.Downlink control information that is conveyed by PDCCH may have attachedCRC. The CRC may be scrambled by the RNTI. For example, the CRC may beXORed with the RNTI. Some examples of the radio network temporaryidentifier (RNTI) include system information RNTI (SI-RNTI), paging RNTI(P-RNTI), cell RNTI (C-RNTI), random access RNTI (RA-RNTI),semi-persistent scheduling C-RNTI (SPS C-RNTI), temporary C-RNTI,transmit power control physical uplink control channel RNTI(TPC-PUCCH-RNTI) and transmit power control physical uplink sharedchannel RNTI (TPC-PUSCH-RNTI). In some cases, the UE may monitor theRNTI (if it is configured to be monitored, for example). The RA-RNTI andthe temporary C-RNTI may be used for PDCCH random access-relatedscheduling information.

However, in order to have multiple time alignments, a UE may need toperform a random access procedure in a PSCell. Thus, a UE configuredwith an SCell with a random access channel may be required to monitor aPDCCH in the common search space in the PSCell in addition to the commonsearch space in the PCell. There may be no need to monitor a SI-RNTI, aP-RNTI and an SPS C-RNTI in the PSCell, since it may be sufficient tomonitor them in the common search space in the PCell. Therefore, theC-RNTI, RA-RNTI, temporary C-RNTI, TPC-PUCCH-RNTI and TPC-PUSCH-RNTI maybe monitored by the UE in the common search space in a PSCell.

Currently, a PCell may not be cross-carrier scheduled. This means that aPDCCH of SCells may not schedule a PDSCH or PUSCH of the PCell. On theother hand, a PCell may schedule other cells. The reason for this isthat the PCell may always be connected and the common search space ofthe PCell may need to be monitored by the UE anyway. It may bebeneficial to use a similar concept regarding a PSCell. Also, the timingdifference between groups may complicate cross-carrier scheduling.Therefore, the PSCell may not be cross-carrier scheduled. In otherwords, the PDCCH of SCells may not schedule a PDSCH or PUSCH of aPSCell. On the other hand, the PSCell may schedule other cells.

A PSCell may be indicated from an eNB to a UE by UE-specific explicit orimplicit RRC signaling. In one example of implicit signaling, an SCellthat is configured with a random access channel is a PSCell. In anotherexample, a PSCell may be an SCell with a lowest order in a groupconfiguration. In yet another example, an SCell configuration has areference cell for uplink timing, which is the PSCell. For example,cells with a Cell Index #0, #1, #2, #3, #4 may be a PCell, SCell #1,SCell #2, SCell #3 and SCell #4, respectively. Continuing with theexample, SCell #2 may have a Cell Index #1 as a reference cell foruplink timing which means SCell #1 is the PSCell for SCell #2. SCell #3may have a Cell Index #0 as a reference cell for uplink timing or noreference cell parameter for uplink timing which means SCell #3 belongsto a group that includes the PCell.

In Release-10, each SCell may use a PCell or the SCell itself as a pathloss reference cell, which may be configurable by RRC signaling. If anSCell uses a PCell as a path loss reference cell, this indicates across-carrier path loss reference. If an SCell uses the SCell as a pathloss reference cell, this indicates a non-cross-carrier path lossreference. In other words, the PCell may be used as a path lossreference cell to other cell(s), but an SCell may not be used as a pathloss reference cell to other cell(s). An RRC parameter“pathlossReference-r10” may be used that indicates which PCell or SCellis used as a reference for a path loss measurement for an SCell. ThisRRC parameter “pathlossReference-r10” (which may be transmitted from aneNB to the UE) may be included in each SCell configuration.

Using different uplink transmission timing among groups may mean thateach group may have different path loss. It may not be useful to selectbetween a PCell and an SCell if the group to which the SCell belongsdoes not include the PCell. If a UE is configured with multiple uplinktime alignments, a “pathlossReference-r11” parameter may be used thatindicates which PSCell or SCell is used as a reference for the path lossmeasurement for an SCell in each SCell configuration. In other words,The PSCell may be used as a path loss reference cell to other cell(s)within its own group. Therefore, the parameter“pathlossReference-r10(pCell, sCell)” may be replaced by a“pathlossReference-r11(psCell, sCell)” parameter in the case that anSCell belongs to a group that does not include the PCell. In anotherconfiguration, a selection among a PCell, a PSCell and an SCell may beused (e.g., a “pathlossReference-r11(pCell, psCell, sCell)” parametermay be used). The pathlossReference-r11 parameter may be sent from aneNB to the UE.

A UE may need to have more than one transmitter in order to performmultiple uplink timing adjustments. In Release-10, carrier aggregationis built as agnostic to the UE transmitter implementation. However, aneNB may need to know whether a UE is capable of supporting multipleuplink time alignments. The UE may inform an eNB of its capability tosupport multiple uplink timing adjustments in a certain band combinationand/or may inform an eNB of the maximum supportable number of uplinktiming adjustments groups. In this way, an eNB may have some informationregarding the transmitter implementation of a UE. Typically, a PUCCH maybe allowed to be assigned only to a PCell because of uplink transmissionpower mitigation. However, if a UE is configured with multiple uplinktime alignments, an eNB may allocate the PUCCH in a PSCell. A periodicchannel quality indicator, precoding matrix indicator and/or rankindicator (CQI/PMI/RI) report on a PUCCH may be modified to be mapped toa PUCCH in a PSCell since their resources may be semi-staticallyassigned using an RRC message. It should be noted that the systems andmethods disclosed herein may be applied to both frequency-divisionduplexing (FDD) systems and time-division duplexing (TDD) systems.Especially in a TDD system, each group may have a differentuplink-downlink configuration that defines subframes for downlink andsubframes for uplink. In a TDD system at least, it may be beneficial foreach group to have a PUCCH.

A hybrid automatic repeat request acknowledgement (HARQ-ACK) (e.g.,acknowledgements or negative acknowledgements (ACK/NACKs)) may also bemapped to a PUCCH in a PSCell. The HARQ-ACK may be generated based oneach group of one or more serving cells. In other words, HARQ-ACK(s)corresponding to cells in a group may be transmitted on a PCell or aPSCell in the group. This approach may be beneficial because it may easehandling buffering issues due to the timing difference between groupssince HARQ processes may be separated into each group.

Some other benefits of the systems and methods disclosed herein are thatan eNB and a UE may operate well in a scenario where multiple uplinktime alignment is needed. Another benefit of the systems and methodsdisclosed herein is that an eNB may allocate resources to a UE formultiple carriers with different physical timing. Yet another benefit ofthe systems and methods disclosed herein is that a UE and an eNB can beimplemented simply. It should be noted that the systems and methodsdisclosed herein may be applicable to carrier aggregation betweenfrequency-division duplex (FDD) systems or between time-division duplex(TDD) systems or even between an FDD system and a TDD system.

Transmission on multiple carrier components (also referred to astransmission on multiple cells, carrier aggregation, transmission onPrimary Cell (PCell) and one or more Secondary Cells (SCells)) may beused in accordance with the systems and methods disclosed herein foruplink (UL) and/or downlink (DL) transmissions.

Various configurations are now described with reference to the Figures,where like reference numbers may indicate functionally similar elements.The systems and methods as generally described and illustrated in theFigures herein could be arranged and designed in a wide variety ofdifferent configurations. Thus, the following more detailed descriptionof several configurations, as represented in the Figures, is notintended to limit scope, as claimed, but is merely representative of thesystems and methods. As used herein the term “plurality” may indicatetwo or more. For example, a plurality of elements refers to two or moreelements.

FIG. 1 is a block diagram illustrating one configuration of a userequipment (UE) 102 and one or more evolved Node Bs (eNBs) 160 in whichsystems and methods for multi-group communications may be implemented.The UE 102 communicates with an evolved Node B (eNB) 160 using one ormore antennas 122 a-n. For example, the UE 102 transmits electromagneticsignals to the eNB 160 and receives electromagnetic signals from the eNB160 using the one or more antennas 122 a-n. The eNB 160 communicateswith the UE 102 using one or more antennas 180 a-n. It should be notedthat the eNB 160 may be a Node B, home evolved Node B (HeNB) or otherkind of base station in some configurations.

The UE 102 and the eNB 160 may use one or more cells (e.g., channels,carrier components, etc.) 119, 121 to communicate with each other. Forexample, the UE 102 and eNB 160 may use the cells 119, 121 to carry oneor more channels (e.g., Physical Uplink Control Channel (PUCCH),Physical Uplink Shared Channel (PUSCH), Physical Downlink ControlChannel (PDCCH), etc.) A PUCCH is one example of a control channelpursuant to 3GPP specifications. Other kinds of channels may be used.

In accordance with the systems and methods disclosed herein, multiplekinds of cells 119, 121 and multiple groups of cells 119, 121 may beused for communication. As used herein, the term “group” may denote agroup of one or more entities. A primary cell (PCell) may be a primarycell in accordance with 3GPP specifications. A secondary cell (SCell)may be a secondary cell in accordance with 3GPP specifications. A groupof one or more cells that includes a PCell may be a PCell group. Cellsin a PCell group may be referred to as PCell group cells 119. Thus, aPCell group includes at least a PCell. A PCell group may additionallyinclude one or more SCells.

One or more other groups of cells that do not include a PCell may eachbe a “non-PCell” group. A non-PCell group may include one or moreSCells. One or more cells in a non-PCell group may be referred to asnon-PCell group cell(s) 121.

In one configuration, cells 119, 121 may be grouped according to site.More specifically, all cells 119, 121 transmitted from a particular site(e.g., eNB 160, repeater, etc.) may be grouped into a group. Forexample, a PCell group may be transmitted from a first site (e.g., aneNB 160 or repeater) while a non-PCell group may be transmitted from asecond site (e.g., a separate remote radio head (RRH) or a separaterepeater, etc.). For instance, a PCell group may be transmitted from afirst eNB 160 at a first location, while a non-PCell group may betransmitted from a second remote radio head at a second location. Aremote radio head (RRH) or repeater is may be a separate transmitter 117and/or receiver 178, but multiple cells may still be provided by asingle eNB 160. In another example, a PCell group may be transmittedfrom a first repeater at a first location, while a non-PCell group maybe transmitted from a second repeater at a second location. In thiscase, the PCell group and the non-PCell group may be transmitted fromthe same site or from separate sites.

The UE 102 may include one or more transceivers 118, one or moredemodulators 114, one or more decoders 108, one or more encoders 150,one or more modulators 154 and an UE multi-group operations module 124.For example, one or more reception and/or transmission paths may be usedin the UE 102. For convenience, only a single transceiver 118, decoder108, demodulator 114, encoder 150 and modulator 154 are illustrated,though multiple parallel elements 118, 108, 114, 150, 154 may be useddepending on the configuration.

The transceiver 118 may include one or more receivers 120 and one ormore transmitters 158. The one or more receivers 120 may receive signalsfrom the eNB 160 using one or more antennas 122 a-n. For example, thereceiver 120 may receive and downconvert signals to produce one or morereceived signals 116. The one or more received signals 116 may beprovided to a demodulator 114. The one or more transmitters 158 maytransmit signals to the eNB 160 using one or more antennas 122 a-n. Forexample, the one or more transmitters 158 may upconvert and transmit oneor more modulated signals 156.

The demodulator 114 may demodulate the one or more received signals 116to produce one or more demodulated signals 112. The one or moredemodulated signals 112 may be provided to the decoder 108. The UE 102may use the decoder 108 to decode signals. The decoder 108 may produceone or more decoded signals 106, 110. For example, a first UE-decodedsignal 106 may comprise received payload data 104. A second UE-decodedsignal 110 may comprise overhead data and/or control data. For example,the second UE-decoded signal 110 may provide data that may be used bythe UE multi-group operations module 124 to perform one or moreoperations.

As used herein, the term “module” may mean that a particular element orcomponent may be implemented in software or a combination of hardwareand software. However, it should be noted that any element denoted as a“module” herein may alternatively be implemented in hardware. Forexample, the UE multi-group operations module 124 may be implemented inhardware, software or a combination of both.

In general, the UE multi-group operations module 124 may enable the UE102 to communicate with one or more eNBs 160 using multiple groups ofone or more cells 119, 121. The UE multi-group operations module 124 mayinclude one or more of a multi-group determination module 126, a PSCelldetermination module 128, a multi-group timing module 130, a multi-groupmonitoring module 132, a multi-group path loss module 134, a multi-groupPUCCH module 136 and a multi-group hybrid automatic repeat request(HARQ) module 138.

The multi-group determination module 126 may use received signalinformation (from the second UE decoded signal 110, for example) todetermine whether the UE 102 may use multiple groups of one or morecells 119, 121 to communicate with one or more eNBs 160. For example,this determination may be based on signaling received from one or moreeNBs 160 that was sent unilaterally or in response to a signal sent fromthe UE 102.

In one configuration, the UE 102 may detect a plurality of cells 119,121. For example, the UE 102 may monitor one or more frequency bands todetect whether one or more eNBs 160 may provide access to cells 119,121. For instance, the UE 102 may receive a broadcast, timing or beaconsignal from one or more eNBs 160 indicating that the one or more eNBs160 may provide cell(s) 119, 121 for communication. In another example,the UE 102 may transmit a signal or message (e.g., a search signal ormessage) to one or more eNBs 160. The one or more eNBs 160 may then senda signal in response to the UE 102 indicating that one or more cells119, 121 may be used for communication.

The multi-group determination module 126 may use additional oralternative information to determine whether to use multiple groups ofone or more cells 119, 121. For example, the UE 102 may determinewhether to use multiple groups of cell(s) 119, 121 based on channel orcell 119, 121 quality, UE 102 capacity, battery life, type of use (e.g.,streaming media, voice call, emergency, etc.) and/or other factors.

The multi-group determination module 126 may also notify one or moreeNBs 160 of the UE's 102 multi-group communications capability. Forexample, A UE 102 may need to have more than one transmitter 158 inorder to perform multiple uplink timing adjustments. In Release-10,carrier aggregation is built as agnostic to a UE transmitterimplementation. However, an eNB 160 may need to know whether a UE 102 iscapable of supporting multiple uplink time alignments. The UE 102 mayinform an eNB 160 (e.g., send a message or signal to the eNB(s) 160) ofits capability to support multiple uplink timing adjustments in acertain band combination and/or may inform an eNB of the maximumsupportable number of uplink timing adjustments groups. In this way, aneNB 160 may have some information regarding the transmitter 158implementation of a UE 102.

The primary secondary cell (PSCell) determination module 128 maydetermine a PSCell for one or more groups of non-PCell group cell(s)121. For example, the UE 102 may communicate with one or more eNBs 160using one or more non-PCell group cells 121 (e.g., groups of non-PCellgroup cell(s) 121). The non-PCell group cell(s) 121 may include one ormore SCells. In some configurations, each non-PCell group may betransmitted via a different site (e.g., eNB 160, repeater, etc.). ThePSCell determination module 128 may determine a primary secondary cell(PSCell) for each non-PCell group.

For example, the PSCell determination module 128 may determine one ormore PSCells based on UE-specific (explicit or implicit) radio resourcecontrol (RRC) signaling. In one example of implicit signaling, an SCell(in a non-PCell group) that is configured with a random access channel(RACH) may be the PSCell for a corresponding non-PCell group. In anotherexample, a PSCell may be an SCell (in a non-PCell group) with a lowestorder in a group configuration. In yet another example, an SCellconfiguration has a reference cell for uplink timing, which is thePSCell. For example, cells with a Cell Index #0, #1, #2, #3, #4 may be aPCell, SCell #1, SCell #2, SCell #3 and SCell #4, respectively.Continuing with the example, SCell #2 may have a Cell Index #1 as areference cell for uplink timing which means SCell #1 is the PSCell forSCell #2. SCell #3 may have a Cell Index #0 as a reference cell foruplink timing or no reference cell parameter for uplink timing whichmeans SCell #3 belongs to a group that includes the PCell.

Alternatively, the PSCell determination module 128 may determine one ormore PSCells based on UE-specific explicit RRC signaling. For example,one or more eNBs 160 may send a message to the UE 102 that explicitlyidentifies one or more PSCells (for one or more non-PCell groups).

The multi-group timing module 130 may control (e.g., adjust) thetransmission timing for one or more groups. For example, the multi-grouptiming module 130 may adjust the transmission timing for one or morenon-PCell groups. For instance, the multi-group timing module 130 mayadvance or delay the timing of non-PCell group signals transmitted fromthe UE 102 to one or more eNBs 160. The transmission timing may bedifferent between the PCell group and one or more non-PCell groups.Additionally or alternatively, the transmission timing may be differentbetween distinct non-PCell groups.

In one configuration, the UE 102 may adjust its uplink transmissiontiming for a physical uplink control channel (PUCCH), physical uplinkshared channel (PUSCH) and/or sounding reference signal (SRS) of aprimary cell (PCell) based on a timing advance command. The timingadvance command in a random access response may be transmitted from aneNB 160 to the UE 102 after the UE 102 has sent a random accesspreamble. Another timing advance command (which refers to a timingadvance command MAC element) may also be transmitted from an eNB 160 tothe UE 102 at any time the eNB 160 wants to change the uplinktransmission timing of the UE 102. The uplink transmission timing mayneed to be adjusted from time to time to account for changes in the RFdelay as the relative position of the UE 102 changes in respect to acorresponding eNB 160. In this manner, the eNB 160 may provide that allsignals from UEs to the eNB 160 reach the eNB 160 at the same time orwithin a cyclic prefix in an orthogonal frequency division multiplexing(OFDM) symbol.

In the case of a random access response, an 11-bit timing advancecommand T_(A) may be used as described above. In other cases, a six-bittiming advance command T_(A) may indicate adjustment of a current N_(TA)value as described above.

Typically, the uplink transmission timing for a physical uplink sharedchannel (PUSCH) and/or sounding reference signal (SRS) of a secondarycell (SCell) may be the same as that of a primary cell (PCell). However,aggregation between cells may be introduced with different transmissionand/or reception sites (e.g., different eNBs 160, RRHs or repeaters,etc.). In this case, the UE 102 may need to have different uplinktransmission timing for each cell or groups of one or more cells. Themulti-group timing module 130 may control or adjust the transmissiontiming for one or more groups (e.g., a PCell group and/or one or morenon-PCell groups).

In one configuration, the uplink transmission timing for a PUSCH and/orSRS of each SCell 119 in a PCell group may be the same as the uplinktransmission timing for the corresponding PCell. In accordance with thesystems and methods disclosed herein, the uplink transmission timing fora PUSCH and/or SRS of each SCell 121 in a non-PCell group may be thesame as the uplink transmission timing for a corresponding PSCell. Itshould be noted that each serving cell 119, 121 has a downlink and mayoptionally have an uplink. Furthermore, each serving downlink carrierand uplink carrier may belong to one serving cell 119, 121.

Uplink transmission timing may need to be adjusted since signals fromthe UE 102 may need to reach one or more eNBs 160 at one or morespecified times. For example, all signals being transmitted to an eNB160 may need to arrive at the same time or within a cyclic prefix in anOFDM symbol at the eNB 160. In 3GPP Release-10, a UE uses the sametransmission timing for all serving cells. In that case, there is noneed to distinguish which cell or group of cells that the timing advancecommand corresponds to since there is only one group for aligning uplinktransmission timing.

A timing advance command in a random access response may be transmittedfrom an eNB 160 and received by the UE 102 in a PCell or in a PSCellafter the UE 102 has sent a random access preamble in the PCell or thePSCell. This random access response may be scheduled by a PDCCHincluding a random access radio network temporary identifier (RA-RNTI),which is an identifier used for scheduling a PDSCH including a randomaccess response.

The PCell or SCell that a received random access response is for may bedistinguished by which serving cell 119, 121 the random access responseis scheduled in. For example, the multi-group timing module 130 maydetermine which cell 119, 121 (e.g., PCell, SCell, etc.) corresponds toa received random access response by determining which serving cell therandom access response is scheduled in. A serving cell that the randomaccess response is scheduled in may be determined by identifying a cell119, 121 that has a HARQ entity, a PDCCH or a PDSCH for a random accessresponse.

In one configuration, the multi-group timing module 130 may thusdetermine which cell 119, 121 corresponds to a received random accessresponse by identifying a cell 119, 121 that has a HARQ entity, a PDCCHor a PDSCH for a random access response. The random access responsescheduled in a PCell downlink (DL) may be used for an uplink (UL)transmission timing adjustment for a PCell uplink. The random accessresponse scheduled in a PSCell downlink (DL) may be used for an uplink(UL) transmission timing adjustment for a PSCell uplink. For example,the multi-group timing module 130 may advance or delay the timing oftransmissions for one or more non-PCell group cells 121 (in one or morenon-PCell groups) based on a corresponding timing advance command. Inone configuration, the uplink transmission timing of SCells 121 in anon-PCell group may be adjusted to match the transmission timing of thePSCell in that group. It should also be noted that PDCCH detection toorder a random access in a PSCell from an eNB to a UE may be in thePSCell and Contention resolution for a random access in a PSCell may bein the PSCell.

Another timing advance command (e.g., a timing advance command MACcontrol element) may be transmitted from an eNB 160 to the UE 102 at anytime the eNB 160 wants to change the UE's 102 uplink transmissiontiming. Whether the received timing advance command is for the PCell orfor a PSCell may be distinguished based on which serving cell 119, 121the timing advance command is scheduled in. A serving cell 119, 121 thatthe timing advance command is scheduled in may be determined byidentifying a cell that has a HARQ entity, a PDCCH or a PDSCH for atiming advance command. For example, the multi-group timing module 130may determine which cell 119, 121 (e.g., PCell, PSCell, etc.) a timingadvance command is for by identifying a cell that has a HARQ entity, aPDCCH or a PDSCH for a timing advance command.

A timing advance command scheduled in any serving cell in a group thatincludes the PCell downlink (e.g., PCell group) may be used for anuplink transmission timing adjustment for the PCell uplink. Thetransmission timing of any SCells in the PCell group may be matched tothat of the PCell.

A timing advance command scheduled in any serving cell(s) in the groupthat includes the PSCell downlink (e.g., a non-PCell group) may be usedfor an uplink transmission timing adjustment for the PSCell uplink. Forexample, the multi-group timing module 130 may advance or delay thetiming of transmissions for one or more non-PCell group cells 121 (inone or more non-PCell groups) based on a corresponding timing advancecommand. The transmission timing of any SCells 121 in a non-PCell groupmay be adjusted to match that of the corresponding PSCell.

In another configuration, the timing advance command MAC control elementor a MAC header of the timing advance command MAC control element mayindicate which group the command corresponds to. A group indication maybe a cell index of a PSCell that is included in the corresponding group.

The multi-group monitoring module 132 may be used to monitor commonsearch spaces for multiple groups. Typically, there is only one commonsearch space in a PCell and there is no common search space in an SCell.However, in accordance with the systems and methods disclosed herein,one or more additional common search spaces may be used in one or morecorresponding PSCell(s). The UE 102 may monitor a set of PDCCHcandidates for control information on one or more activated servingcells 119, 121 as configured by higher layer signaling. More than oneserving cell 119, 121 may be configured by RRC signaling and a servingcell may be activated or deactivated by MAC signaling.

The set of PDCCH candidates to monitor may be defined in terms of searchspaces. Typically, there is a common search space on the primary cell(PCell) 119 and a UE-specific search space on the PCell 119 and/or oneor more SCells. In this case, the common search space may becell-specific and only on the PCell 119. The UE-specific search spacemay be defined by a cell radio network temporary identifier or C-RNTI(e.g., user equipment identifier (UEID)) and may be prepared for eachserving cell 119, 121.

Typically, different kinds of information or data may be transmitted ina common search space. For example, a PDCCH to schedule systeminformation or paging information, random access related information ornormal UE 102 transmission data 146 may be transmitted in the commonsearch space. The physical layer of a UE 102 may be configured by higherlayers with a RNTI. The UE 102 may decode the PDCCH with a cyclicredundancy check (CRC) scrambled by the RNTI. Downlink controlinformation that is conveyed by PDCCH may have attached CRC. The CRC maybe scrambled by the RNTI. For example, the CRC may be XORed with theRNTI. Some examples of the radio network temporary identifier (RNTI)include system information RNTI (SI-RNTI), paging RNTI (P-RNTI), cellRNTI (C-RNTI), random access RNTI (RA-RNTI), semi-persistent schedulingC-RNTI (SPS C-RNTI), temporary C-RNTI, transmit power control physicaluplink control channel RNTI (TPC-PUCCH-RNTI) and transmit power controlphysical uplink shared channel RNTI (TPC-PUSCH-RNTI). In some cases, theUE 102 may monitor the RNTI (if it is configured to be monitored, forexample). The RA-RNTI and the temporary C-RNTI may be used for PDCCHrandom access-related scheduling information.

However, in accordance with the systems and methods disclosed herein andin order to have multiple time alignments, the UE 102 may need toperform a random access procedure in a PSCell 121. Thus, a UE 102configured with an SCell with a random access channel (RACH) may berequired to monitor a PDCCH in a common search space in the PSCell 121in addition to the common search space in the PCell 119. There may be noneed to monitor a SI-RNTI, a P-RNTI and an SPS C-RNTI in the PSCell 121,since it may be sufficient to monitor them in the common search space inthe PCell 119. Therefore, the C-RNTI, RA-RNTI, temporary C-RNTI,TPC-PUCCH-RNTI and TPC-PUSCH-RNTI may be monitored by the multi-groupmonitoring module 132 in the common search space in a PSCell 121.

The multi-group path loss module 134 may be used to produce one or morepath loss indicators for one or more non-PCell groups. In oneconfiguration, the multi-group path loss module 134 may additionally beused to produce a path loss indicator for a PCell group. For example, inthe case that an SCell 121 belongs to a non-PCell group, the multi-grouppath loss module 134 may produce a path loss indicator corresponding toa designated cell 121. A cell 121 used to measure the path loss may bedesignated by a “pathlossReference-r11(psCell, sCell)” parameter insteadof a typical path loss parameter “pathlossReference-r10(pCell, sCell)”.

In Release-10, for example, each SCell may use a PCell or the SCellitself as a path loss reference cell, which may be configurable by RRCsignaling. If an SCell uses a PCell as a path loss reference cell, thisindicates a cross-carrier path loss reference. If an SCell uses theSCell as a path loss reference cell, this indicates a non-cross-carrierpath loss reference. In other words, the PCell may be used as a pathloss reference cell to other cell(s), but an SCell may not be used as apath loss reference cell to other cell(s). An RRC parameter“pathlossReference-r10” may be used that indicates which PCell or SCellis used as a reference for a path loss measurement for an SCell in eachSCell configuration. This RRC parameter “pathlossReference-r10” (whichmay be transmitted from an eNB to the UE) may be included in each SCellconfiguration. However, in accordance with the systems and methodsdisclosed herein, using different uplink transmission timing amonggroups may mean that each group may have a different path loss. It maynot be useful to select between a PCell 119 and an SCell 121 if thegroup to which the SCell 121 belongs does not include the PCell 119. Ifthe UE 102 is configured with multiple uplink time alignments, a“pathlossReference-r11” parameter may be used that indicates whichPSCell 121 or SCell 121 is used as a reference for the path lossmeasurement for an SCell 121 in each SCell configuration. Therefore, thetypical parameter “pathlossReference-r10(pCell, sCell)” may be replacedby a “pathlossReference-r11(psCell, sCell)” parameter in the case thatan SCell 121 belongs to a non-PCell group. In another configuration, aselection among a PCell, a PSCell and an SCell may be used (e.g., a“pathlossReference-r11(pCell, psCell, sCell)” parameter may be used).The pathlossReference-r11 parameter may be sent from an eNB to the UE.

The multi-group PUCCH module 136 may configure one or more PUCCHscorresponding to one or more non-PCell groups. For example, a PSCell 121may have a PUCCH in addition to a PUCCH corresponding to the PCell 119.Typically, a PUCCH may be allowed to be assigned only to a PCell 119because of uplink transmission power mitigation. However, if the UE 102is configured with multiple uplink time alignments, an eNB 160 mayallocate the PUCCH in a PSCell 121. A periodic channel qualityindicator, precoding matrix indicator and/or rank indicator (CQI/PMI/RI)report on a PUCCH may be modified to be mapped to a PUCCH in a PSCell121 since their resources may be semi-statically assigned using an RRCmessage.

The multi-group HARQ module 138 may generate one or more ACK/NACKs forone or more non-PCell groups. For example, a hybrid automatic repeatrequest acknowledgement (HARQ-ACK) corresponding to non-PCell groupcells 121 in a group may be transmitted on the PSCell 121 in the group.

A hybrid automatic repeat request acknowledgement (HARQ-ACK) mayoptionally be mapped to a PUCCH in a PSCell 121. The HARQ-ACK may begenerated based on each group of one or more serving cells 121. In someconfigurations, HARQ-ACK(s) corresponding to cells 119, 121 in a groupmay be transmitted on a PCell 119 or a PSCell 121 in the group. Thisapproach may ease handling buffering issues due to the timing differencebetween groups since HARQ processes may be separated into each group.

The UE multi-group operations module 124 may provide information 142 tothe encoder 150. This information 142 may include instructions for theencoder 150 and/or data to be encoded. For example, the UE multi-groupoperations module 124 may instruct the encoder 150 to shift transmissiontiming, instruct the encoder 150 regarding an encoding rate and/or typefor one or more non-PCell groups and/or instruct the encoder 150regarding transmission data 146 mapping to one or more non-PCell PUCCHs.Additionally or alternatively, the information 142 may include data tobe encoded, such as a message indicating a UE 102 multi-groupcapability, ACK/NACKs for one or more non-PCell groups and/or one ormore path loss indicators for one or more non-PCell groups.

The encoder 150 may encode transmission data 146 and/or otherinformation 142 provided by the UE multi-group operations module 124.For example, encoding the data 146 and/or other information 142 mayinvolve error detection and/or correction coding, mapping data to space,time and/or frequency resources (e.g., space-time block coding (STBC))for transmission, etc. The encoder 150 may provide encoded data 152 tothe modulator 154.

The UE multi-group operations module 124 may provide information 144 tothe modulator 154. This information 144 may include instructions for themodulator 154. For example, the UE multi-group operations module 124 mayinstruct the modulator 154 to shift transmission timing and/or instructthe modulator 154 regarding a modulation type (e.g., constellationmapping) for one or more non-PCell groups. The modulator 154 maymodulate the encoded data 152 to provide one or more modulated signals156 to the one or more transmitters 158.

The UE multi-group operations module 124 may provide information 140 tothe one or more transmitters 158. This information 140 may includeinstructions for the one or more transmitters 158. For example, the UEmulti-group operations module 124 may instruct the one or moretransmitters 158 to shift transmission timing for one or more non-PCellgroups. The one or more transmitters 158 may upconvert and transmit themodulated signal(s) 156 to one or more eNBs 160. It should be noted thatthe UE 102 may need to have more than one transmitter 158 in order toperform multiple uplink timing adjustments.

Each of the one or more eNBs 160 may include one or more transceivers176, one or more demodulators 172, one or more decoders 166, one or moreencoders 109, one or more modulators 113 and an eNB group operationsmodule 182. For example, one or more reception and/or transmission pathsmay be used in an eNB 160. For convenience, only a single transceiver176, decoder 166, demodulator 172, encoder 109 and modulator 113 areillustrated, though multiple parallel elements 176, 166, 172, 109, 113may be used depending on the configuration.

The transceiver 176 may include one or more receivers 178 and one ormore transmitters 117. The one or more receivers 178 may receive signalsfrom the UE 102 using one or more antennas 180 a-n. For example, thereceiver 178 may receive and downconvert signals to produce one or morereceived signals 174. The one or more received signals 174 may beprovided to a demodulator 172. The one or more transmitters 117 maytransmit signals to the UE 102 using one or more antennas 180 a-n. Forexample, the one or more transmitters 117 may upconvert and transmit oneor more modulated signals 115.

The demodulator 172 may demodulate the one or more received signals 174to produce one or more demodulated signals 170. The one or moredemodulated signals 170 may be provided to the decoder 166. The eNB 160may use the decoder 166 to decode signals. The decoder 166 may produceone or more decoded signals 164, 168. For example, a first eNB-decodedsignal 164 may comprise received payload data 162. A second eNB-decodedsignal 168 may comprise overhead data and/or control data. For example,the second UE-decoded signal 168 may provide data that may be used bythe eNB group operations module 182 to perform one or more operations.

In general, the eNB group operations module 182 may enable the eNB 160to communicate with a UE 102 that is using multiple groups of one ormore cells 119, 121. The eNB group operations module 182 may include oneor more of a group transmission module 196, a PSCell designation module194, a group timing module 186, a group scheduling module 192, a grouppath loss module 190, a group PUCCH module 184 and a multi-group hybridautomatic repeat request (HARQ) module 188.

The group transmission module 196 may determine a group transmissioncapability of the UE 102. For example, the group transmission module 196may use received signal information (from the second UE decoded signal168, for example) to determine whether the UE 102 may use multiplegroups of one or more cells 119, 121 to communicate with one or moreeNBs 160. As described above, the UE 102 may need to have multipletransmitters 158 to use multiple transmission timing alignments. Thereceived signal information may indicate whether the UE 102 is capableof multiple timing adjustments (in a certain band combination) and/ormay indicate a maximum supportable number of uplink timing adjustmentsgroups, for instance. This determination may be based on signalingreceived from the UE 102 that was sent unilaterally or in response to asignal sent from the eNB 160.

The primary secondary cell (PSCell) designation module 194 may designatea PSCell for one or more groups of non-PCell group cell(s) 121. Forexample, the eNB 160 may communicate with the UE 102 using one or morenon-PCell group cells 121. The non-PCell group cell(s) 121 may includeone or more SCells. The eNB 160 may communicate using one or morenon-PCell groups (e.g., groups of non-PCell group cell(s) 121). In someconfigurations, each non-PCell group may be transmitted via a differentsite (e.g., RRH, repeater, etc.). The PSCell designation module 194 maygenerate and/or send a message to the UE designating a primary secondarycell (PSCell) for one or more non-PCell groups.

For example, the PSCell designation module 194 may designate one or morePSCells using UE-specific (explicit or implicit) radio resource control(RRC) signaling. In one example of implicit signaling, an SCell (in anon-PCell group) that is configured with a random access channel (RACH)may be the PSCell for a corresponding non-PCell group. In anotherexample, a PSCell may be an SCell (in a non-PCell group) with a lowestorder in a group configuration. In yet another example, an SCellconfiguration has a reference cell for uplink timing, which is thePSCell. For example, cells with a Cell Index #0, #1, #2, #3, #4 may be aPCell, SCell #1, SCell #2, SCell #3 and SCell #4, respectively.Continuing with the example, SCell #2 may have a Cell Index #1 as areference cell for uplink timing which means SCell #1 is the PSCell forSCell #2. SCell #3 may have a Cell Index #0 as a reference cell foruplink timing or no reference cell parameter for uplink timing whichmeans SCell #3 belongs to a group that includes the PCell.

Alternatively, the PSCell designation module 194 may designate one ormore PSCells using UE-specific explicit RRC signaling. For example, theeNB 160 may send a message to the UE 102 that explicitly identifies oneor more PSCells (for one or more non-PCell groups).

The group timing module 186 may manage the transmission timing for oneor more groups. For example, the group timing module 186 may send atiming adjustment message (e.g., timing advance command) to the UE 102to adjust the transmission timing for one or more non-PCell groups. Forinstance, the UE 102 may advance or delay the timing of non-PCell groupsignals transmitted from the UE 102 corresponding to an eNB 160 based onone or more timing advance commands sent from the eNB 160. Thetransmission timing may be different between the PCell group and one ormore non-PCell groups. Additionally or alternatively, the transmissiontiming may be different between distinct non-PCell groups.

In one configuration, the UE 102 may adjust its uplink transmissiontiming for a physical uplink control channel (PUCCH), physical uplinkshared channel (PUSCH) and/or sounding reference signal (SRS) of aprimary cell (PCell) based on a timing advance command (e.g., message)from an eNB 160. The timing advance command in a random access responsemay be transmitted from an eNB 160 to the UE 102 after the UE 102 hassent a random access preamble (to the eNB 160). Another timing advancecommand (which refers to a timing advance command MAC element) is alsotransmitted from an eNB 160 to the UE 102 at any time the eNB 160 wantsto change the uplink transmission timing of the UE 102. The uplinktransmission timing may need to be adjusted from time to time to accountfor changes in the RF delay as the relative position of the UE 102changes in respect to a corresponding eNB 160. In this manner, the eNB160 may provide that all signals from UEs to the eNB 160 reach the eNB160 at the same time or within a cyclic prefix in an orthogonalfrequency division multiplexing (OFDM) symbol.

In the case of a random access response, an 11-bit timing advancecommand T_(A) may be sent from the eNB 160 as described above. In othercases, a six-bit timing advance command T_(A) may be sent from the eNB160 and may indicate adjustment of a current N_(TA) value as describedabove.

Typically, the uplink transmission timing for a physical uplink sharedchannel (PUSCH) and/or sounding reference signal (SRS) of a secondarycell (SCell) may be the same as that of a primary cell (PCell). However,aggregation between cells may be introduced with different transmissionand/or reception sites (e.g., different eNBs, RRHs or repeaters, etc.).In this case, the eNB 160 may need to have different uplink transmissiontiming for each cell or groups of one or more cells. The group timingmodule 186 may generate and send commands to control or adjust thetransmission timing for one or more groups (e.g., a PCell group and/orone or more non-PCell groups).

A timing advance command in a random access response may be transmittedfrom an eNB 160 and received by the UE 102 in a PCell or in a PSCellafter the UE 102 has sent a random access preamble in the PCell or thePSCell. This random access response may be scheduled by a PDCCHincluding a random access radio network temporary identifier (RA-RNTI),which is an identifier used for scheduling a PDSCH including a randomaccess response. The PCell or SCell that a random access response is formay be indicated by which serving cell 119, 121 the random accessresponse is scheduled in. A serving cell that the random access responseis scheduled in may be indicated by a cell 119, 121 that has a HARQentity, a PDCCH or a PDSCH for a random access response.

Another timing advance command (e.g., a timing advance command MACelement) may be transmitted from an eNB 160 to the UE 102 at any time aneNB 160 wants to change the UE's 102 uplink transmission timing. Whetherthe received timing advance command is for the PCell or for a PSCell maybe indicated based on which serving cell 119, 121 the timing advancecommand is scheduled in. For example, which cell 119, 121 (e.g., PCell,PSCell, etc.) a timing advance command is for may be indicated by a cellthat has a HARQ entity, a PDCCH or a PDSCH for a timing advance command.

In some configurations, the eNB 160 may use a timing advance command MACcontrol element or a MAC header of the timing advance command MACcontrol element that may indicate which group the command correspondsto. A group indication may be a cell index of a PSCell that is includedin the corresponding group.

The group scheduling module 192 may be used to schedule communicationsfor one or more groups of cells 119, 121. For example, the groupscheduling block/module 192 may allocate communication resources to theUE 102 by sending a random access response to the UE 102. As notedabove, a random access response may also include a timing advancecommand as generated by the group timing module 186. In some instances,scheduling information may be sent to the UE 102 using a PDCCH.

For example, a PDCCH to schedule system information or paginginformation may be transmitted by an eNB 160. The physical layer of a UE102 may be configured by higher layers with a RNTI. Downlink controlinformation that is conveyed by PDCCH may have attached CRC. The eNB 160may scramble the CRC using the RNTI. For example, the CRC may be XORedwith the RNTI. The RA-RNTI and the temporary C-RNTI may be used forPDCCH random access-related scheduling information. As described above,a PSCell may not be cross-carrier scheduled, but may schedule one ormore SCells.

The group path loss module 190 may be used to manage one or more pathloss parameters for one or more non-PCell groups. For example, in thecase that an SCell 121 belongs to a non-PCell group, the group path lossmodule 190 may generate a path loss parameter (e.g.,pathlossReference-r11(psCell, sCell)) in order to designate a non-PCellgroup cell 121 as a path loss reference instead of a typical path lossparameter (e.g., pathlossReference-r10(pCell, sCell)). The path lossparameter may designate a cell used by a UE 102 to measure a path loss.

The group PUCCH module 184 may be used to allocate one or more PUCCHscorresponding to one or more non-PCell groups. For example, a PSCell 121may have a PUCCH in addition to a PUCCH corresponding to the PCell 119.Typically, a PUCCH may be allowed to be assigned only to a PCell 119because of uplink transmission power mitigation. However, if the UE 102is configured with multiple uplink time alignments, an eNB 160 mayallocate the PUCCH in a PSCell 121.

The group HARQ module 188 may receive one or more ACK/NACKs for one ormore non-PCell groups. An eNB 160 may use the one or more ACK/NACKs toretransmit information that was not correctly received by the UE 102.ACK/NACKs corresponding to non-PCell group cells 121 in a group may bereceived by the eNB 160 on the PSCell 121 in the group. ACK/NACK(s) mayoptionally be mapped to a PUCCH in a PSCell 121. In some configurations,HARQ-ACK(s) corresponding to cells 119, 121 in a group may be receivedon a PCell 119 or a PSCell 121 in the group. This approach may bebeneficial, since it may ease handling buffering issues due to thetiming difference between groups since HARQ processes may be separatedinto each group.

The eNB group operations module 182 may provide information 101 to theencoder 109. This information 101 may include instructions for theencoder 109 and/or data to be encoded. For example, the eNB groupoperations module 182 may instruct the encoder 109 regarding an encodingrate and/or type for one or more non-PCell groups and/or instruct theencoder 109 regarding transmission data 105 mapping to one or morenon-PCell PUCCHs. Additionally or alternatively, the information 101 mayinclude data to be encoded, such as a message indicating a timingadvance command, scheduling information, channel allocations and/orother control information.

The encoder 109 may encode transmission data 105 and/or otherinformation 101 provided by the eNB group operations module 182. Forexample, encoding the data 105 and/or other information 101 may involveerror detection and/or correction coding, mapping data to space, timeand/or frequency resources (e.g., space-time block coding (STBC)) fortransmission, etc. The encoder 109 may provide encoded data 111 to themodulator 113. The transmission data 105 may include network data to berelayed to the UE 102.

The eNB group operations module 182 may provide information 103 to themodulator 113. This information 103 may include instructions for themodulator 113. For example, the eNB group operations module 182 mayinstruct the modulator 113 regarding a modulation type (e.g.,constellation mapping) for one or more non-PCell groups. The modulator113 may modulate the encoded data 111 to provide one or more modulatedsignals 115 to the one or more transmitters 117.

The eNB group operations module 182 may provide information 198 to theone or more transmitters 117. This information 198 may includeinstructions for the one or more transmitters 117. For example, the eNBgroup operations module 182 may instruct the one or more transmitters117 to form one or more non-PCell group cell(s) 121. The one or moretransmitters 117 may upconvert and transmit the modulated signal(s) 115to the UE 102.

FIG. 2 is a flow diagram illustrating one configuration of a method 200for performing multi-group communications on a UE 102. A UE 102 maydetect 202 a plurality of cells 119, 121. For example, the UE 102 mayreceive a synchronization signal, a beacon, a message, etc., from one ormore eNBs 160 indicating that multiple groups of one or more cells 119,121 may be used for communications. Additionally or alternatively, theUE 102 may send a signal or message (e.g., an access request,authentication information, etc.) to one or more eNBs 160 indicatingthat the UE 102 is seeking to communicate with the one or more eNBs 160.In this case, the one or more eNBs 160 may respond by sending a signalthat allows the UE 102 to communicate with the one or more eNBs 160.

The UE 102 may determine 204 whether to use multiple groups of cells119, 121 to communicate. If the UE 102 determines 204 not to communicateusing multiple groups of cells 119, 121, the UE 102 may communicate 206using a single group of cells 119. In some configurations, the UE 102may determine 204 not to communicate using multiple groups of cells 119,121, if the UE 102 is incapable of communicating using multiple groupsof cells 119, 121 or for other considerations (e.g., low battery power,poor channel quality with a non-PCell group, etc.).

If the UE 102 determines 204 to communicate using multiple groups ofcells 119, 121, the UE 102 may determine 208 a PSCell 121 for eachnon-PCell group. For example, the UE 102 may communicate with one ormore eNBs 160 using one or more non-PCell group cells 121 (e.g., groupsof non-PCell group cell(s) 121). The non-PCell group cell(s) 121 mayinclude one or more SCells. In some configurations, each non-PCell groupmay be transmitted from a different site (e.g., eNB 160, RRH, repeater,etc.). The PSCell determination module 128 may determine a primarysecondary cell (PSCell) for each non-PCell group.

For example, the UE 102 may determine 208 one or more PSCells based onUE-specific (explicit or implicit) radio resource control (RRC)signaling. In one example of implicit signaling, an SCell (in anon-PCell group) that is configured with a random access channel (RACH)may be determined 208 as the PSCell for a corresponding non-PCell group.In another example, a PSCell may be determined 208 as an SCell (in anon-PCell group) with a lowest order in a group configuration. In yetanother example, an SCell configuration has a reference cell for uplinktiming, which is the PSCell. For example, cells with a Cell Index #0,#1, #2, #3, #4 may be a PCell, SCell #1, SCell #2, SCell #3 and SCell#4, respectively. Continuing with the example, SCell #2 may have a CellIndex #1 as a reference cell for uplink timing which means SCell #1 isthe PSCell for SCell #2. SCell #3 may have a Cell Index #0 as areference cell for uplink timing or no reference cell parameter foruplink timing which means SCell #3 belongs to a group that includes thePCell.

Alternatively, UE 102 may determine 208 one or more PSCells based onUE-specific explicit RRC signaling. For example, the UE 102 may receivea message from one or more eNBs 160 that explicitly identifies one ormore PSCells (for one or more non-PCell groups).

The UE 102 may determine 210 whether to adjust transmission timing. Forexample, if the UE 102 has received one or more timing advance commandsfrom one or more eNBs 160, the UE 102 may determine 210 to adjust uplinktransmission timing. However, if the UE 102 has not received anytransmission advance commands, the UE 102 may determine 210 not toadjust uplink transmission timing.

If the UE 102 determines 210 to adjust uplink transmission timing, thenthe UE 102 may use 212 a timing advance command to adjust uplink timingfor a group of cells 119, 121. For example, the UE 102 may adjust thetransmission timing for one or more non-PCell groups. For instance, theUE 102 may advance or delay the timing of non-PCell group signalstransmitted from the UE 102 to one or more eNBs 160 by using 212 atiming advance command that specifies the amount of time delay oradvancement. The transmission timing may be different between the PCellgroup and one or more non-PCell groups. Additionally or alternatively,the transmission timing may be different between distinct non-PCellgroups.

In one configuration, the UE 102 may adjust its uplink transmissiontiming for a physical uplink control channel (PUCCH), physical uplinkshared channel (PUSCH) and/or sounding reference signal (SRS) of aprimary cell (PCell) by using 212 a received timing advance command. Thetiming advance command received in a random access response may betransmitted from an eNB 160 to the UE 102 after the UE 102 has sent arandom access preamble. Another received timing advance command (whichrefers to a timing advance command MAC element) may be transmitted froman eNB 160 to the UE 102 at any time the eNB 160 wants to change theuplink transmission timing of the UE 102.

In the case of a random access response, an 11-bit timing advancecommand T_(A) may be used as described above. In other cases, a six-bittiming advance command T_(A) may indicate adjustment of a current N_(TA)value as described above.

Typically, the uplink transmission timing for a physical uplink sharedchannel (PUSCH) and/or sounding reference signal (SRS) of a secondarycell (SCell) may be the same as that of a primary cell (PCell). However,aggregation between cells may be introduced with different transmissionand/or reception sites (e.g., different eNBs, RRHs or repeaters, etc.).In this case, the UE 102 may need to have different uplink transmissiontiming for each cell or groups of one or more cells. The UE 102 maycontrol or adjust the transmission timing for one or more groups (e.g.,a PCell group and/or one or more non-PCell groups).

In one configuration, the uplink transmission timing for a PUSCH and/orSRS of each SCell 119 in a PCell group may be the same as the uplinktransmission timing for the corresponding PCell. In accordance with thesystems and methods disclosed herein, the uplink transmission timing fora PUSCH and/or SRS of each SCell 121 in a non-PCell group may be thesame as the uplink transmission timing for a corresponding PSCell.

A timing advance command in a random access response may be used 212that is transmitted from an eNB 160 and received by the UE 102 in aPCell or in a PSCell after the UE 102 has sent a random access preamblein the PCell or the PSCell. This random access response may be scheduledby a PDCCH including a random access radio network temporary identifier(RA-RNTI), which is an identifier used for scheduling a PDSCH includinga random access response.

The PCell or SCell that a received random access response is for may bedistinguished by which serving cell 119, 121 the random access responseis scheduled in. For example, the UE 102 may determine which cell 119,121 (e.g., PCell, SCell, etc.) corresponds to a received random accessresponse by determining which serving cell the random access response isscheduled in. A serving cell that the random access response isscheduled in may be determined by identifying a cell 119, 121 that has aHARQ entity, a PDCCH or a PDSCH for a random access response.

In one configuration, the UE 102 may thus determine which cell 119, 121corresponds to a received random access response by identifying a cell119, 121 that has a HARQ entity, a PDCCH or a PDSCH for a random accessresponse. The random access response scheduled in a PCell downlink (DL)may be used for an uplink (UL) transmission timing adjustment for aPCell uplink. The random access response scheduled in a PSCell downlink(DL) may be used for an uplink (UL) transmission timing adjustment for aPSCell uplink. For example, the UE 102 may advance or delay the timingof transmissions for one or more non-PCell group cells 121 (in one ormore non-PCell groups) based on a corresponding timing advance command.In one configuration, the transmission timing of SCells 121 in anon-PCell group may be adjusted to match the transmission timing of thePSCell in that group.

Another received timing advance command (e.g., a timing advance commandMAC element) may be transmitted from an eNB 160 to the UE 102 at anytime the eNB 160 wants to change the UE's 102 uplink transmissiontiming. Whether the received timing advance command is for the PCell orfor a PSCell may be distinguished based on which serving cell 119, 121the timing advance command is scheduled in. A serving cell 119, 121 thatthe timing advance command is scheduled in may be determined byidentifying a cell that has a HARQ entity, a PDCCH or a PDSCH for atiming advance command. For example, the UE 102 may determine which cell119, 121 (e.g., PCell, PSCell, etc.) a timing advance command is for byidentifying a cell that has a HARQ entity, a PDCCH or a PDSCH for atiming advance command.

A timing advance command scheduled in any serving cell in a group thatincludes the PCell downlink (e.g., PCell group) may be used 212 for anuplink transmission timing adjustment for the PCell uplink. Thetransmission timing of any SCells in the PCell group may be matched tothat of the PCell.

A timing advance command scheduled in any serving cell(s) in the groupthat includes the PSCell downlink (e.g., a non-PCell group) may be used212 for an uplink transmission timing adjustment for the PSCell uplink.For example, the UE 102 may advance or delay the timing of transmissionsfor one or more non-PCell group cells 121 (in one or more non-PCellgroups) based on a corresponding timing advance command. Thetransmission timing of any SCells 121 in a non-PCell group may beadjusted to match that of the corresponding PSCell.

In another configuration, the timing advance command MAC control elementor a MAC header of the timing advance command MAC control element mayindicate which group the command corresponds to. A group indication maybe a cell index of a PSCell that is included in the corresponding group.

Whether or not the UE 102 determines 210 to adjust transmission timing,the UE 102 may determine 214 whether a path loss parameter is receivedthat designates a reference cell 121 in a non-PCell group. For example,if the UE 102 receives a “pathlossReference-r11(psCell, sCell)”parameter, then the UE 102 may determine 214 that a path loss parameteris received that designates a reference cell 121 in a non-PCell group.However, if the UE 102 does not receive any path loss parameter (orreceives a “pathlossReference-r10(pCell, sCell),” for example), then theUE 102 may determine 214 that no path loss parameter is received thatdesignates a reference cell 121 in a non-PCell group.

If the UE 102 determines 214 that a path loss parameter is received thatdesignates a reference cell 121 in a non-PCell group, then the UE 102may determine 216 a path loss based on the reference cell 121. Forexample, the UE 102 may determine a received signal strength for thedesignated cell 121 and determine 216 the path loss based on thereceived signal strength. For instance, the UE 102 may subtract thereceived signal strength from a transmitted signal strength (asindicated by an eNB 160) to determine 216 the path loss. In someconfigurations, the UE 102 may generate a path loss indicator fortransmission to an eNB 160 in order to indicate the path loss.

Whether or not the UE 102 determines 214 that a path loss parameter wasreceived that designates a reference cell 121 in a non-PCell group, theUE 102 may communicate 218 with one or more eNBs 160 using the multiplegroups. For example, the UE 102 may transmit information to and/orreceive information from one or more eNBs 160 using one or more PCellgroup cells 119 and one or more non-PCell group cells 121.

FIG. 3 is a block diagram illustrating one configuration of a UEmulti-group operation module 324 that may be used in accordance with thesystems and methods disclosed herein. In general, the UE multi-groupoperations module 324 may enable the UE 102 to communicate with one ormore eNBs 160 using multiple groups of one or more cells 119, 121. TheUE multi-group operations module 324 may include one or more of amulti-group determination module 326, a PSCell determination module 328,a multi-group timing module 330 and a multi-group path loss module 334.

The multi-group determination block/module 326 may generate multi-groupcontrol information 331. Some or all of the multi-group controlinformation 331 may be provided used by the UE 102 and/or transmitted toone or more eNBs 160 in order to allow multi-group communications.

The multi-group determination module 326 may use received signalinformation 323 to determine whether the UE 102 may use multiple groupsof one or more cells 119, 121 to communicate with one or more eNBs 160.For example, this determination may be based on signaling received fromone or more eNBs 160 that was sent unilaterally or in response to asignal sent from the UE 102.

In one configuration, the UE 102 may detect a plurality of cells 119,121. For example, the UE 102 may monitor the received signal information323 (e.g., one or more frequency bands) to detect whether one or moreeNBs 160 may provide access to cells 119, 121. For instance, the UE 102may receive a broadcast, timing or beacon signal (e.g., received signalinformation 323) from one or more eNBs 160 indicating that the one ormore eNBs 160 may provide cell(s) 119, 121 for communication. In anotherexample, the UE 102 may transmit a signal or message (e.g., a searchsignal or message) to one or more eNBs 160. The one or more eNBs 160 maythen send a signal in response to the UE 102 indicating that one or morecells 119, 121 may be used for communication.

The multi-group determination module 326 may use additional oralternative information to determine whether to use multiple groups ofone or more cells 119, 121. For example, the UE 102 may determinewhether to use multiple groups of cell(s) 119, 121 based on channel orcell 119, 121 quality, UE 102 capacity, battery life, type of use (e.g.,streaming media, voice call, emergency, etc.) and/or other factors. Themulti-group control information 331 may indicate whether multi-groupcommunications are to be used. This indication may be provided to the UE102 to enable the UE 102 to use multiple groups of cells 119, 121.

The multi-group determination module 326 may also notify one or moreeNBs 160 of the UE's 102 multi-group communications capability. Forexample, A UE 102 may need to have more than one transmitter 158 inorder to perform multiple uplink timing adjustments. The multi-groupcontrol information 331 may be transmitted to inform an eNB 160 of theUE's 102 capability to support multiple uplink timing adjustments in acertain band combination and/or may inform an eNB 160 of the maximumsupportable number of uplink timing adjustments groups.

The primary secondary cell (PSCell) determination module 328 maydetermine a PSCell for one or more groups of non-PCell group cell(s)121. In one configuration, the PSCell determination block/module 328 mayuse PSCell designation information 325 to produce PSCell information333. The PSCell information 333 may indicate a primary secondary cell(PSCell) for each non-PCell group.

For example, the PSCell determination module 328 may produce PSCellinformation 333 based on the PSCell designation information 325. In oneconfiguration, the PSCell designation information 325 may be UE-specific(explicit or implicit) radio resource control (RRC) signaling. In oneexample of implicit signaling, an SCell (in a non-PCell group) that isconfigured with a random access channel (RACH) may be determined as thePSCell for a corresponding non-PCell group. In another example, a PSCellmay be determined as an SCell (in a non-PCell group) with a lowest orderin a group configuration. In yet another example, an SCell configurationhas a reference cell for uplink timing, which is the PSCell. Forexample, cells with a Cell Index #0, #1, #2, #3, #4 may be a PCell,SCell #1, SCell #2, SCell #3 and SCell #4, respectively. Continuing withthe example, SCell #2 may have a Cell Index #1 as a reference cell foruplink timing which means SCell #1 is the PSCell for SCell #2. SCell #3may have a Cell Index #0 as a reference cell for uplink timing or noreference cell parameter for uplink timing which means SCell #3 belongsto a group that includes the PCell.

Alternatively, the PSCell determination module 328 may determine one ormore PSCells based on explicit PSCell designation information 325 (e.g.,UE-specific explicit RRC signaling). For example, one or more eNBs 160may send a message to the UE 102 that explicitly identifies one or morePSCells (for one or more non-PCell groups). In this case, the PSCelldetermination module 328 may indicate the one or more designated PSCellsin the PSCell information 333.

The multi-group timing module 330 may control (e.g., adjust) thetransmission timing for one or more groups based on one or more timingadvance commands 327. The multi-group timing module 330 may produce oneor more timing adjustments 335. For example, the timing adjustment(s)335 may adjust the transmission timing for one or more non-PCell groups.For instance, a timing adjustment 335 may use the timing advancecommand(s) 327 to advance or delay the timing of non-PCell group signalstransmitted from the UE 102 to one or more eNBs 160.

The multi-group timing module 330 may adjust timing as described inconnection with the multi-group timing module 130 in FIG. 1. Forexample, a timing advance command 327 may be included in a random accessresponse or may be a MAC element. The multi-group timing module 330 maydetermine which cell(s) 119, 121 a timing advance command 327corresponds to as described above.

The multi-group timing module 330 may then generate one or more timingadjustment(s) 335 to advance or delay the transmission timing of one ormore cells 119, 121 by an amount indicated by the timing advancecommand(s) 327. For example, the timing adjustment(s) 335 may indicatethat a PCell uplink radio frame (and any uplink radio framescorresponding to any SCells 119 in the PCell group) should be adjustedto precede a PCell downlink radio frame by a certain amount of time.Additionally or alternatively, the timing adjustment(s) 335 may indicatethat a PSCell uplink radio frame (and any uplink radio framescorresponding to any SCells 121 in a corresponding PSCell group) shouldbe adjusted to precede a PSCell downlink radio frame by a certain amountof time.

The multi-group path loss module 334 may be used to produce one or morepath loss indicators 337 based on path loss information 329 for one ormore non-PCell groups. In one configuration, the multi-group path lossmodule 334 may additionally be used to produce a path loss indicator 337based on path loss information 329 for a PCell group. For example, inthe case that an SCell 121 belongs to a non-PCell group, the multi-grouppath loss module 334 may produce a path loss indicator 337 correspondingto a designated cell 121. A cell 121 used to measure the path loss maybe designated by path loss information 329 (e.g., a“pathlossReference-r11(psCell, sCell)” parameter instead of a typicalpath loss parameter “pathlossReference-r10(pCell, sCell)”).

If the UE 102 is configured with multiple uplink time alignments, a“pathlossReference-r11” parameter may be included in path lossinformation 329 that indicates which PSCell 121 or SCell 121 is used asa reference for the path loss measurement for an SCell 121 in each SCellconfiguration. Therefore, the typical parameter“pathlossReference-r10(pCell, sCell)” may be replaced by a“pathlossReference-r11(psCell, sCell)” parameter in the case that anSCell 121 belongs to a non-PCell group. In another configuration, aselection among a PCell, a PSCell and an SCell may be used (as indicatedby path loss information 329, for example). More specifically, aselection among a PCell, a PSCell and an SCell may be used (e.g., a“pathlossReference-r11(pCell, psCell, sCell)” parameter may be used).The pathlossReference-r11 parameter may be sent from an eNB to the UE.

FIG. 4 is a flow diagram illustrating a more specific configuration of amethod 400 for performing multi-group communications on a UE 102. A UE102 may detect 402 a plurality of cells 119, 121. For example, the UE102 may detect 402 a plurality of cells 119, 121 as described inconnection with step 202 of FIG. 2 above.

The UE 102 may transmit 404 information to one or more eNBs 160indicating a multiple uplink time alignment capability. For example, theUE 102 may transmit 404 a message or signal to the one or more eNBs 160indicating that the UE 102 is capable of using multiple time alignments.For instance, this may indicate that the UE 102 has multipletransmitters 158.

The UE 102 may determine 406 whether to use multiple groups of cells119, 121 to communicate. For example, this may done as described inconnection with step 204 of FIG. 2 above. If the UE 102 determines 406not to communicate using multiple groups of cells 119, 121, the UE 102may communicate 408 using a single group of cells 119.

If the UE 102 determines 406 to communicate using multiple groups ofcells 119, 121, the UE 102 may determine 410 a PSCell 121 for eachnon-PCell group. This may be done as described in connection with step208 of FIG. 2 above.

The UE 102 may monitor 412 a common search space for each of one or moregroups. Typically, there is only one common search space in a PCell andthere is no common search space in an SCell. However, in accordance withthe systems and methods disclosed herein, one or more additional commonsearch spaces may be used in one or more corresponding PSCell(s). The UE102 may monitor 412 a set of PDCCH candidates for control information onone or more activated serving cells 119, 121 as configured by higherlayer signaling. More than one serving cell 119, 121 may be configuredby RRC signaling and a serving cell may be activated or deactivated byMAC signaling.

The set of PDCCH candidates to monitor 412 may be defined in terms ofsearch spaces. Typically, there is a common search space on the primarycell (PCell) 119 and a UE-specific search space on the PCell 119 and/orone or more SCells. In this case, the common search space may becell-specific and only on the PCell 119. The UE-specific search spacemay be defined by a cell radio network temporary identifier or C-RNTI(e.g., user equipment identifier (UEID)) and may be prepared for eachserving cell 119, 121.

Typically, different kinds of information or data may be transmitted ina common search space. For example, a PDCCH to schedule systeminformation or paging information, random access related information ornormal UE 102 transmission data 146 may be transmitted in the commonsearch space. The physical layer of a UE 102 may be configured by higherlayers with a RNTI. The UE 102 may decode the PDCCH with a cyclicredundancy check (CRC) scrambled by the RNTI. Downlink controlinformation that is conveyed by PDCCH may have attached CRC. The CRC maybe scrambled by the RNTI. For example, the CRC may be XORed with theRNTI. In some cases, the UE 102 may monitor 412 the RNTI (if it isconfigured to be monitored, for example). The RA-RNTI and the temporaryC-RNTI may be used for PDCCH random access-related schedulinginformation.

However, in accordance with the systems and methods disclosed herein andin order to have multiple time alignments, the UE 102 may need toperform a random access procedure in a PSCell 121. Thus, a UE 102configured with an SCell with a random access channel (RACH) may berequired to monitor 412 a PDCCH in the common search space in the PSCell121 in addition to the common search space in the PCell 119. There maybe no need to monitor a SI-RNTI, a P-RNTI and an SPS C-RNTI in thePSCell 121, since it may be sufficient to monitor 412 them in the commonsearch space in the PCell 119. Therefore, the C-RNTI, RA-RNTI, temporaryC-RNTI, TPC-PUCCH-RNTI and TPC-PUSCH-RNTI may be monitored 412 by themulti-group monitoring module 132 in the common search space in a PSCell121.

The UE 102 may optionally configure 414 a PUCCH for one or morenon-PCell groups if allocated by an eNB 160. For example, a PSCell 121may have a PUCCH in addition to a PUCCH corresponding to the PCell 119.Typically, a PUCCH may be allowed to be assigned only to a PCell 119because of uplink transmission power mitigation. However, if the UE 102is configured with multiple uplink time alignments, an eNB 160 mayallocate the PUCCH in a PSCell 121. For example, the UE 102 may receivea message or command from one or more eNBs 160 allocating a PUCCH forone or more non-PCell groups. The UE 102 may accordingly configure 414(e.g., establish, send control information on, etc.) a PUCCH for one ormore non-PCell groups as indicated by the one or more eNBs 160. Itshould be noted that a periodic channel quality indicator, precodingmatrix indicator and/or rank indicator (CQI/PMI/RI) report on a PUCCHmay be modified to be mapped to a PUCCH in a PSCell 121 since theirresources may be semi-statically assigned using an RRC message.

The UE 102 may determine 416 whether to adjust transmission timing. Forexample, if the UE 102 has received one or more timing advance commandsfrom one or more eNBs 160, the UE 102 may determine 416 to adjusttransmission timing. However, if the UE 102 has not received anytransmission timing commands, the UE 102 may determine 416 not to adjusttransmission timing.

If the UE 102 determines 416 to adjust transmission timing, then the UE102 may use 418 a timing advance command to adjust uplink timing for agroup of cells 119, 121. For example, this may be done as described inconnection with step 212 of FIG. 2 above.

Whether or not the UE 102 determines 416 to adjust transmission timing,the UE 102 may determine 420 whether a path loss parameter is receivedthat designates a reference cell 121 in a non-PCell group. For example,this may be done as described in connection with step 214 of FIG. 2above.

If the UE 102 determines 420 that a path loss parameter is received thatdesignates a reference cell 121 in a non-PCell group, then the UE 102may determine 422 a path loss based on the reference cell 121. Forexample, this may be done as described in connection with step 216 ofFIG. 2 above. The UE 102 may transmit 424 a path loss indicator. Forexample, the UE 102 may generate a path loss indicator based on the pathloss determined 422. The path loss indicator may specify the path lossas measured by the UE 102 for the reference cell. The UE 102 maytransmit 424 this path loss indicator to an eNB 160.

Whether or not the UE 102 determines 420 that a path loss parameter wasreceived that designates a reference cell 121 in a non-PCell group, theUE 102 may optionally transmit 426 one or more HARQ-ACK(s) (e.g.,ACK/NACKs) on a PSCell for each non-PCell group. For example, a HARQ-ACKmessage (e.g., one or more ACK/NACKs) may be generated based on eachgroup of one or more serving cells 121. For instance, when a specifiedamount of data (e.g., packet) is incorrectly received (and isunrecoverable, for example), the UE 102 may generate and transmit 426 anegative acknowledgement (NACK).

Additionally or alternatively, the UE 102 may generate and transmit 426an acknowledgement (ACK) for a specified amount of data (e.g., packet)that was correctly received. In some configurations, HARQ-ACK(s)corresponding to cells 121 in a group may be transmitted 426 on a PSCell121 in the group. Optionally, HARQ-ACK(s) corresponding to cells 119 ina PCell group may be transmitted on the PCell 119. In the case that aPUCCH is configured 414 for at least one non-PCell groups, a HARQ-ACKmessage (e.g., one or more ACK/NACKs) may optionally be mapped to aPUCCH in a PSCell 121.

The UE 102 may communicate 428 with one or more eNBs 160 using themultiple groups. For example, the UE 102 may transmit information toand/or receive information from one or more eNBs 160 using one or morePCell group cells 119 and one or more non-PCell group cells 121.

FIG. 5 is a block diagram illustrating another configuration of a UEmulti-group operation module 524 that may be used in accordance with thesystems and methods disclosed herein. In general, the UE multi-groupoperations module 524 may enable the UE 102 to communicate with one ormore eNBs 160 using multiple groups of one or more cells 119, 121. TheUE multi-group operations module 524 may include one or more of amulti-group determination module 526, a PSCell determination module 528,a multi-group timing module 530, a multi-group monitoring module 532, amulti-group path loss module 534, a multi-group PUCCH module 536 and amulti-group HARQ module 538.

The multi-group determination block/module 526 may generate multi-groupcontrol information 531. Some or all of the multi-group controlinformation 531 may be used by the UE 102 and/or transmitted to one ormore eNBs 160 in order to allow multi-group communications. Themulti-group determination module 526 may also use received signalinformation 523. For example, the multi-group determination module 526may operate similar to the multi-group determination module 326described in connection with FIG. 3 above.

The primary secondary cell (PSCell) determination module 528 maydetermine a PSCell for one or more groups of non-PCell group cell(s)121. In one configuration, the PSCell determination block/module 528 mayuse PSCell designation information 525 to produce PSCell information533. The PSCell information 533 may indicate a primary secondary cell(PSCell) for each non-PCell group. For example, the PSCell determinationmodule 528 may operate similar to the PSCell determination module 328described in connection with FIG. 3 above.

The multi-group timing module 530 may control (e.g., adjust) the uplinktransmission timing for one or more groups based on one or more timingadvance commands 527. The multi-group timing module 530 may produce oneor more timing adjustments 535. For example, the timing adjustment(s)535 may adjust the transmission timing for one or more non-PCell groups.For instance, a timing adjustment 535 may use the timing advancecommand(s) 527 to advance or delay the timing of non-PCell group signalstransmitted from the UE 102 to one or more eNBs 160. The multi-grouptiming module 530 may adjust timing similar to the multi-group timingmodule 330 described in connection with FIG. 3 above.

The multi-group monitoring module 532 may be used to monitor commonsearch spaces for multiple groups. For example, the multi-groupmonitoring module 532 may use downlink information 539 (e.g., one ormore PDCCH candidates) to produce multi-group control information 545.In accordance with the systems and methods disclosed herein, one or moreadditional common search spaces may be used in one or more correspondingPSCell(s). The UE 102 may monitor a set of PDCCH candidates for controlinformation on one or more activated serving cells 119, 121 asconfigured by higher layer signaling. More than one serving cell 119,121 may be configured by RRC signaling and a serving cell may beactivated or deactivated by MAC signaling.

The set of PDCCH candidates (e.g., the downlink information 539) tomonitor may be defined in terms of search spaces. Typically, there is acommon search space on the primary cell (PCell) 119 and a UE-specificsearch space on the PCell 119 and/or one or more SCells. In this case,the common search space may be cell-specific and only on the PCell 119.The UE-specific search space may be defined by a cell radio networktemporary identifier or C-RNTI (e.g., user equipment identifier (UEID))and may be prepared for each serving cell 119, 121.

Different kinds of information or data may be transmitted in a commonsearch space. For example, a PDCCH to schedule system information orpaging information, random access related information or normal UE 102transmission data 146 may be transmitted in the common search space. Themulti-group control information 545 generated by the multi-groupmonitoring module 532 may identify or include such information (e.g.,system information or paging information scheduling, random accessrelated information, etc.). This multi-group control information 545 maybe used to control communications for one or more groups (e.g.,non-PCell groups).

The physical layer of a UE 102 may be configured by higher layers with aRNTI. The UE 102 may decode the PDCCH with a cyclic redundancy check(CRC) scrambled by the RNTI. Downlink (control) information 539 that isconveyed by a PDCCH may have attached CRC. The CRC may be scrambled bythe RNTI (and may be unscrambled by the UE 102). For example, the CRCmay be XORed with the RNTI. In some cases, the UE 102 may monitor theRNTI (if it is configured to be monitored, for example). The RA-RNTI andthe temporary C-RNTI may be used for PDCCH random access-relatedscheduling information.

In accordance with the systems and methods disclosed herein and in orderto have multiple time alignments, the UE 102 may need to perform arandom access procedure in a PSCell 121. Thus, a UE 102 configured withan SCell with a random access channel (RACH) may be required to monitora PDCCH in the common search space in the PSCell 121 in addition to thecommon search space in the PCell 119. There may be no need to monitor aSI-RNTI, a P-RNTI and an SPS C-RNTI in the PSCell 121, since it may besufficient to monitor them in the common search space in the PCell 119.Therefore, the C-RNTI, RA-RNTI, temporary C-RNTI, TPC-PUCCH-RNTI andTPC-PUSCH-RNTI (which may occur in the downlink information 539) may bemonitored by the multi-group monitoring module 532 in the common searchspace in a PSCell 121.

The multi-group path loss module 534 may be used to produce one or morepath loss indicators 537 based on path loss information 529 for one ormore non-PCell groups. In one configuration, the multi-group path lossmodule 534 may additionally be used to produce a path loss indicator 537based on path loss information 529 for a PCell group. For example, themulti-group path loss module 534 may operate similar to the multi-grouppath loss module 334 described in connection with FIG. 3 above.

The multi-group PUCCH module 536 may configure one or more PUCCHscorresponding to one or more non-PCell groups. For example, themulti-group PUCCH module 536 may generate PUCCH configurationinformation 547 based on allocation information 541. For instance, aPSCell 121 may have a PUCCH in addition to a PUCCH corresponding to thePCell 119. Typically, a PUCCH may be allowed to be assigned only to aPCell 119 because of uplink transmission power mitigation. However, ifthe UE 102 is configured with multiple uplink time alignments, an eNB160 may allocate the PUCCH in a PSCell 121. More specifically, the UE102 may receive allocation information 541 from one or more eNBs 160indicating a command or request to establish one or more PUCCHs. Basedon the allocation information 541, the multi-group PUCCH module 536 mayprovide PUCCH configuration information 547 (e.g., channel information,timing information, etc.) that allows the UE 102 to establish one ormore PUCCHs with one or more eNBs 160. A periodic channel qualityindicator, precoding matrix indicator and/or rank indicator (CQI/PMI/RI)report on a PUCCH may be modified to be mapped to a PUCCH in a PSCell121 since their resources may be semi-statically assigned using an RRCmessage.

The multi-group HARQ module 538 may generate one or more group ACK/NACKs549 for one or more non-PCell groups based on error information 543. Theerror information 543 may specify information that was not correctlyreceived from one or more eNBs 160 and/or that could not be recovered.The multi-group HARQ module 538 may generate one or more group ACK/NACKs549 corresponding to the incorrectly received or unrecoverableinformation. The group ACK/NACKs 549 may correspond to (e.g., be mappedto) one or more particular cells. For example, a hybrid automatic repeatrequest acknowledgement (HARQ-ACK) corresponding to non-PCell groupcells 121 in a group may be transmitted on the PSCell 121 in the group.

A hybrid automatic repeat request acknowledgement (HARQ-ACK) mayoptionally be mapped to a PUCCH in a PSCell 121. The HARQ-ACK may begenerated based on each group of one or more serving cells 121. In someconfigurations, HARQ-ACK(s) (e.g., ACK/NACKs) corresponding to cells119, 121 in a group may be transmitted on a PCell 119 or a PSCell 121 inthe group.

FIG. 6 is a flow diagram illustrating one configuration of a method 600for performing multi-group communications on an eNB 160. An eNB 160 mayoptionally receive 602 information indicating a UE 102 multiple uplinktime alignment capability. For example, the eNB 160 may receiveinformation or a message from a UE 102 indicating that the UE 102 iscapable of using multiple uplink transmission timing alignments. Morespecifically, this information or message may inform the eNB 160 of theUE's 102 capability to support multiple uplink timing adjustments in acertain band combination and/or may inform an eNB 160 of the maximumsupportable number of uplink timing adjustments groups. In someconfigurations, the eNB 160 may initially query a UE 102 (e.g., send amessage to the UE 102) whether the UE 102 is capable of supportingmultiple uplink timing adjustments.

The eNB 160 may transmit 604 radio resource control (RRC) signalingindicating one or more PSCells. For example, the eNB 160 may designateone or more PSCells by sending UE-specific (explicit or implicit) radioresource control (RRC) signaling. In one example of implicit signaling,an SCell (in a non-PCell group) that is configured with a random accesschannel (RACH) may be the PSCell for a corresponding non-PCell group. Inthis example, signaling that indicates or designates a RACH may indicatea PSCell designation to the UE 102. In another example, a PSCell may bean SCell (in a non-PCell group) with a lowest order in a groupconfiguration. Thus, signaling from the eNB 160 that may be used toestablish an SCell order may indicate the PSCell, for instance. In yetanother example, an SCell configuration has a reference cell for uplinktiming, which is the PSCell. For example, cells with a Cell Index #0,#1, #2, #3, #4 may be a PCell, SCell #1, SCell #2, SCell #3 and SCell#4, respectively. Continuing with the example, SCell #2 may have a CellIndex #1 as a reference cell for uplink timing which means SCell #1 isthe PSCell for SCell #2. SCell #3 may have a Cell Index #0 as areference cell for uplink timing or no reference cell parameter foruplink timing which means SCell #3 belongs to a group that includes thePCell.

Alternatively, the eNB 160 may designate one or more PSCells usingUE-specific explicit RRC signaling. For example, the eNB 160 may send amessage to the UE 102 that explicitly identifies one or more PSCells(for one or more non-PCell groups).

The eNB 160 may determine 606 whether to adjust timing. In oneconfiguration, the eNB 160 may use a signal or message sent from the UE102 (e.g., random access request, etc.) to determine whether to adjustuplink timing. For example, the eNB 160 may determine whether one ormore uplink transmissions from the UE 102 arrive within a certain timeframe or schedule. If an uplink transmission from the UE 102 is notaligned or synchronized to be within a certain time frame, the eNB 160may determine 606 to adjust timing. However, if an uplink transmissionfrom the UE 102 is within the time frame, the eNB 160 may determine 606not to adjust timing. In some configurations, the time frame may bedefined in terms of a cyclic prefix in an orthogonal frequency divisionmultiplexing (OFDM) symbol. Additionally or alternatively, the timeframe may be specified in terms of a difference in time between adownlink radio frame and an uplink radio frame. It should be noted thatthe term “synchronize” and variations thereof may or may not denote anexact alignment in time, but may denote an overlapping of events orevents occurring within a range of time from each other.

If the eNB 160 determines 606 to adjust timing, the eNB 160 may transmit608 one or more timing advance commands. For example, the eNB 160 maysend a timing advance command to the UE 102 to adjust the transmissiontiming for one or more non-PCell groups. This may cause the UE 102 toadvance or delay the timing of non-PCell group signals transmitted fromthe UE 102 corresponding to an eNB 160 based on one or more timingadvance commands sent from the eNB 160.

A timing advance command in a random access response may be transmitted608 from an eNB 160 to the UE 102 after the UE 102 has sent a randomaccess preamble (to the eNB 160). Another timing advance command (whichrefers to a timing advance command MAC element) may be transmitted 608from an eNB 160 to the UE 102 at any time the eNB 160 wants to changethe uplink transmission timing of the UE 102. The uplink transmissiontiming may be adjusted from time to time to account for changes in theRF delay as the relative position of the UE 102 changes in respect to acorresponding eNB 160. In this manner, the eNB 160 may provide that allsignals from UEs to the eNB 160 reach the eNB 160 at approximately thesame time or within a cyclic prefix in an orthogonal frequency divisionmultiplexing (OFDM) symbol. One configuration of timing advance commandsis given as follows.

In the case of a random access response, an 11-bit timing advancecommand T_(A) may indicate N_(TA) values by index values of T_(A)=0, 1,2, K, 1282, where an amount of the time alignment is given byN_(TA)=T_(A)×16.

In other cases, a six-bit timing advance command T_(A) may indicateadjustment of a current N_(TA) value (denoted N_(TA,old)) to a newN_(TA) value (denoted N_(TA,new)) by index values of T_(A)=0, 1, 2, K,63, where N_(TA,new) N_(TA,old)+(T_(A)−31)×16. In this case, adjustmentof an N_(TA) value by a positive or a negative amount indicatesadvancing or delaying the uplink transmission timing by a given amount,respectively.

Whether or not the eNB 160 determines 606 to adjust timing, the eNB 160may optionally transmit 610 control information using one or more cellgroups. For example, the eNB 160 may schedule communications for one ormore groups of cells 119, 121. For instance, the eNB 160 may allocatecommunication resources to the UE 102 by sending a random accessresponse to the UE 102. In some instances, scheduling information may besent to the UE 102 using a PDCCH.

For example, a PDCCH to schedule system information or paginginformation may be transmitted by an eNB 160. The physical layer of a UE102 may be configured by higher layers with a RNTI. Downlink controlinformation that is conveyed by PDCCH may have attached CRC. The eNB 160may scramble the CRC using the RNTI. For example, the CRC may be XORedwith the RNTI. The RA-RNTI and the temporary C-RNTI may be used forPDCCH random access-related scheduling information.

In one configuration, a PSCell may not be cross-carrier scheduled. Thismeans that other cells may not schedule a PSCell. On the other hand, aPSCell may schedule other cells. Thus, for example, the eNB 160 mayschedule one or more SCells and/or a PSCell using the PSCell. However,the eNB 160 may not schedule a PSCell using a separate SCell.

The eNB 160 may optionally transmit 612 one or more path lossparameters. This may be done for one or more non-PCell groups, forexample. In one configuration, the eNB 160 may manage one or more pathloss parameters for one or more non-PCell groups. For example, in thecase that an SCell 121 belongs to a non-PCell group, the eNB 160 maygenerate a path loss parameter (e.g., pathlossReference-r11(psCell,sCell)) in order to designate a non-PCell group cell 121 as a path lossreference instead of a typical path loss parameter (e.g.,pathlossReference-r10(pCell, sCell)). The eNB 160 may transmit 612 thispath loss parameter to the UE 102. The path loss parameter may designatea cell used by a UE 102 to measure a path loss.

The eNB 160 may optionally receive 614 one or more path loss indicators.For example, the eNB 160 may receive a path loss indicator (from the UE102) that indicates a path loss as measured by the UE 102 correspondingto the reference cell designated by a transmitted 612 path lossparameter. The eNB 160 may use the path loss indicator to adjusttransmissions (e.g., increase or decrease the amplification for asignal) to the UE 102.

The eNB 160 may optionally allocate 616 a PUCCH for a PSCell. Forexample, the eNB 160 may allocate 616 one or more PUCCHs correspondingto one or more non-PCell groups. For example, a PSCell 121 may have aPUCCH in addition to a PUCCH corresponding to the PCell 119. Forinstance, if the UE 102 is configured with multiple uplink timealignments, an eNB 160 may allocate the PUCCH in a PSCell 121. In oneconfiguration, the eNB 160 sends a configuration message or request tothe UE 102 commanding or requesting the UE 102 to establish a PUCCH (ina PSCell 121).

The eNB 160 may optionally receive 618 one or more ACK/NACKs on one ormore PSCells (e.g., for one or more non-PCell groups). ACK/NACKscorresponding to non-PCell group cells 121 in a group may be received618 by the eNB 160 on the PSCell 121 in the group. ACK/NACK(s) mayoptionally be mapped to a PUCCH in a PSCell 121. In some configurations,HARQ-ACK(s) corresponding to cells 119, 121 in a group may be receivedon a PCell 119 or a PSCell 121 in the group. An eNB 160 may use the oneor more ACK/NACKs to retransmit information that was not correctlyreceived by the UE 102.

The eNB 160 may communicate 620 with a UE 102 using one or more cellgroups. For example, the eNB 160 may send information to and/or receiveinformation from the UE 102 using one or more PCell group cells 119 andone or more non-PCell group cells 121.

FIG. 7 is a block diagram illustrating one configuration of an eNB groupoperations module 782 that may be used to enable multi-groupcommunications on an eNB 160. In general, the eNB group operationsmodule 782 may enable an eNB 160 to communicate with a UE 102 that isusing multiple groups of one or more cells 119, 121. The eNB groupoperations module 782 may include one or more of a group transmissionmodule 796, a PSCell designation module 794, a group timing module 786,a group scheduling module 792, a group path loss module 790, a groupPUCCH module 784 and a group hybrid automatic repeat request (HARQ)module 788.

The group transmission module 796 may determine a group transmissioncapability of the UE 102. For example, the group transmission module 796may use received signal information 707 to determine whether the UE 102may use multiple groups of one or more cells 119, 121 to communicatewith one or more eNBs 160. As described above, the UE 102 may need tohave multiple transmitters to use multiple transmission timingalignments. The received signal information 707 may indicate whether theUE 102 is capable of multiple timing adjustments (in a certain bandcombination) and/or may indicate a maximum supportable number of uplinktiming adjustments groups, for instance. This determination may be basedon signaling received from the UE 102 that was sent unilaterally or inresponse to a signal sent from the eNB 160.

The group transmission module 796 may generate group configurationinformation 757 based on its determination of whether the UE 102 iscapable of supporting multi-group communications. The groupconfiguration information 757 may be used to configure communicationswith the UE 102. For instance, the group configuration information 757may be used to determine whether to establish additionally communicationchannel(s) (e.g., cells 121) with the UE 102, whether to send PSCelldesignation information, etc.

The primary secondary cell (PSCell) designation module 794 may designatea PSCell for one or more groups of non-PCell group cell(s) 121. Forexample, the eNB 160 may generate PSCell designation information 759that designates a particular SCell as a PSCell. In some cases and/orconfigurations, the PSCell designation information 759 may be generatedbased on a group communication request 751 received from the UE 102. Forexample, the PSCell designation information 759 may be sent to a UE 102in response to a random access request. Alternatively, the eNB 160 mayunilaterally generate and send the PSCell designation information 759 tothe UE 102.

For example, the PSCell designation module 794 may designate one or morePSCells using UE-specific (explicit or implicit) radio resource control(RRC) signaling. In one example of implicit signaling, an SCell (in anon-PCell group) that is configured with a random access channel (RACH)may be implicitly designated as the PSCell for a corresponding non-PCellgroup. In another example, a PSCell may be designated as an SCell (in anon-PCell group) with a lowest order in a group configuration. In yetanother example, an SCell configuration has a reference cell for uplinktiming, which is the PSCell. For example, cells with a Cell Index #0,#1, #2, #3, #4 may be a PCell, SCell #1, SCell #2, SCell #3 and SCell#4, respectively. Continuing with the example, SCell #2 may have a CellIndex #1 as a reference cell for uplink timing which means SCell #1 isthe PSCell for SCell #2. SCell #3 may have a Cell Index #0 as areference cell for uplink timing or no reference cell parameter foruplink timing which means SCell #3 belongs to a group that includes thePCell.

Alternatively, the PSCell designation module 794 may designate one ormore PSCells using UE-specific explicit RRC signaling. For example, theeNB 160 may send PSCell designation information 759 to the UE 102 thatexplicitly identifies one or more PSCells (for one or more non-PCellgroups).

The group timing module 786 may manage the transmission timing for oneor more groups. For example, the group timing module 786 may send atiming advance command 761 to the UE 102 to adjust the transmissiontiming for one or more non-PCell groups. For instance, the eNB 102 mayobtain timing information 753 that indicates a difference in timebetween a given time and a received uplink radio frame from the UE 102.Based on this difference, the eNB 102 may generate one or more timingadvance commands 761. The eNB 160 may transmit the one or more timingadvance commands 761. For example, the group timing module 786 may senda timing advance command 761 to the UE 102 to adjust the transmissiontiming for one or more non-PCell groups. This may cause the UE 102 toadvance or delay the timing of non-PCell group signals transmitted fromthe UE 102 corresponding to an eNB 160 based on one or more timingadvance commands 761 sent from the eNB 160.

A timing advance command 761 in a random access response may betransmitted from an eNB 160 to the UE 102 after the UE 102 has sent arandom access preamble (e.g., group communication request 751) to theeNB 160. Another timing advance command 761 (which refers to a timingadvance command MAC element) may be transmitted from an eNB 160 to theUE 102 at any time the eNB 160 wants to change the uplink transmissiontiming of the UE 102. The uplink transmission timing may be adjustedfrom time to time to account for changes in the RF delay as the relativeposition of the UE 102 changes in respect to a corresponding eNB 160. Inthis manner, the eNB 160 may provide that all signals from UEs to theeNB 160 reach the eNB 160 at approximately the same time or within acyclic prefix in an orthogonal frequency division multiplexing (OFDM)symbol. One configuration of timing advance commands 761 is given asfollows.

In the case of a random access response, an 11-bit timing advancecommand T_(A) 761 may indicate N_(TA) values by index values of T_(A)=0,1, 2, K, 1282, where an amount of the time alignment is given byN_(TA)=T_(A)×16.

In other cases, a six-bit timing advance command T_(A) 761 may indicateadjustment of a current N_(TA) value (denoted N_(TA,old)) to a newN_(TA) value (denoted N_(TA,new)) by index values of T_(A)=0, 1, 2, K,63, where N_(TA,new)=N_(TA,old)+(T_(A)−31)×16. In this case, adjustmentof an N_(TA) value by a positive or a negative amount indicatesadvancing or delaying the uplink transmission timing by a given amount,respectively.

The group scheduling module 792 may be used to schedule communicationsfor one or more groups of cells 119, 121. For example, the groupscheduling block/module 792 may generate multi-group control information763 that allocates communication resources to the UE 102 by sending arandom access response to the UE 102. This may be done in response to agroup communication request 751 (e.g., random access request). In someinstances, scheduling information (e.g., multi-group control information763) may be sent to the UE 102 using a PDCCH.

For example, a PDCCH (including multi-group control information 763, forinstance) to schedule system information or paging information may betransmitted by an eNB 160. The physical layer of a UE 102 may beconfigured by higher layers with a RNTI. Multi-group (downlink) controlinformation 763 that is conveyed by PDCCH may have attached CRC. The eNB160 may scramble the CRC using the RNTI. For example, the CRC may beXORed with the RNTI. The RA-RNTI and the temporary C-RNTI may be usedfor PDCCH random access-related scheduling information.

In one configuration, a PSCell may not be cross-carrier scheduled. Thismeans that other cells may not schedule a PSCell. On the other hand, aPSCell may schedule other cells. Thus, for example, the eNB 160 may usemulti-group configuration information 763 to schedule one or more SCellsand/or a PSCell using the PSCell. However, the eNB 160 may not schedulea PSCell using a separate SCell.

The group path loss module 790 may be used to manage one or more pathloss parameters for one or more non-PCell groups. For example, in thecase that an SCell 121 belongs to a non-PCell group, the group path lossmodule 790 may generate one or more path loss parameters 765 (e.g.,pathlossReference-r11(psCell, sCell)) in order to designate a non-PCellgroup cell 121 as a path loss reference instead of a typical path lossparameter (e.g., pathlossReference-r10(pCell, sCell)). The one or morepath loss parameters 765 may be transmitted to the UE 102. The path lossparameter 765 may designate a cell used by a UE 102 to measure a pathloss.

The group PUCCH module 784 may be used to generate PUCCH configurationinformation 767 that allocates one or more PUCCHs corresponding to oneor more non-PCell groups. For example, a PSCell 121 may have a PUCCH inaddition to a PUCCH corresponding to the PCell 119. Typically, a PUCCHmay be allowed to be assigned only to a PCell 119 because of uplinktransmission power mitigation. However, if the UE 102 is configured withmultiple uplink time alignments, an eNB 160 may allocate the PUCCH in aPSCell 121 by sending PUCCH configuration information 767 to the UE 102.

The group HARQ module 788 may receive one or more ACK/NACKs 755 for oneor more non-PCell groups. An eNB 160 may use the one or more ACK/NACKs755 to retransmit information that was not correctly received by the UE102. For example, the group HARQ module 788 may generate retransmissioninformation 769. The retransmission information 769 may specify data tobe retransmitted to the UE 102.

ACK/NACKs 755 corresponding to non-PCell group cells 121 in a group maybe received by the eNB 160 on the PSCell 121 in the group. ACK/NACK(s)755 may optionally be mapped to a PUCCH in a PSCell 121. In someconfigurations, HARQ-ACK(s) 755 corresponding to cells 119, 121 in agroup may be received on a PCell 119 or a PSCell 121 in the group.

FIG. 8 is a diagram illustrating one example of uplink transmissiontiming. Transmission of an uplink radio frame number i 875 from the UE102 may start N_(TA)×T_(s) seconds 873 before the start of acorresponding downlink radio frame i 871 at the UE 102, where0≤N_(TA)≤20512 and

$T_{s} = \frac{1}{( {15000 \times 2048} )}$seconds. In other words, a UE 102 may begin transmitting an uplink radioframe i 875 N_(TA)×T_(s) seconds 873 before receiving a correspondingdownlink radio frame i 871.

FIG. 9 is a diagram illustrating another example of uplink transmissiontiming. The uplink transmission timing of one or more SCells (e.g., forPUSCH and/or SRS) is the same as the PCell. As illustrated in FIG. 9,the transmission of a PCell uplink radio frame number i 979 from the UE102 may start N_(TA)×T_(s) seconds 981 before the start of acorresponding PCell downlink radio frame i 977 at the UE 102. Thetransmission of one or more SCell uplink radio frames number i 985 a-cfrom the UE 102 may start N_(TA)×T_(s) seconds 981 before the start ofthe PCell downlink radio frame i 977 at the UE 102. As can be observedin FIG. 9, downlink radio frames number i 983 a-c may vary in timing.

FIG. 10 is a block diagram illustrating one example of a deploymentscenario. In this example, two eNBs 1060 a-b may both communicate with aUE 1002. eNB A 1060 a may include one or more antennas 1080 a-m forcommunicating with the UE 1002. eNB B 1060 b may include one or moreantennas 1080 n-z for communicating with the UE 1002. The UE 1002 mayinclude antennas 1022 a-n for communicating with eNB A 1060 a and eNB B1060 b. In this example, the UE 1002 may communicate with twonon-collocated sites (e.g., eNBs 1060 a-b) on multiple carriers. As canbe observed, each communication path 1087 a-b may experience differentpropagation environments. This may lead to differences in uplinktransmission timing for communication frames on path A 1087 a and path B1087 b. In one configuration, one group of cells or channels may beestablished on path A 1087 a, while another group of cells or channelsmay be established on path B 1087 b. The scenario illustrated in FIG. 10could similarly occur with remote antennas or remote radio heads.

FIG. 11 is a block diagram illustrating another example of a deploymentscenario. In this example, an eNB 1160 may communicate with a UE 1102using multiple signals. The eNB 1160 may include one or more antennas1180 a-n for communicating with the UE 1102 via repeaters A and B 1189a-b. Repeater A 1189 a may include one or more antennas 1191 a-m forcommunicating with the eNB 1160 and/or the UE 1102. Repeater B 1189 bmay include one or more antennas 1191 n-z for communicating with the eNB1160 and/or the UE 1102. The UE 1102 may include antennas 1122 a-n forcommunicating with the eNB 1160 via repeaters A and B 1189 a-b. In thisexample, the UE 1102 may communicate with the eNB 1160 over paths A andB 1187 a-b. As can be observed, each communication path 1187 a-b mayexperience different propagation environments. This may lead todifferences in uplink transmission timing for communication frames onpath A 1187 a and path B 1187 b. For example, different componentcarriers could see substantially different propagation environmentsbetween path A 1187 a and path B 1187 b due to differentfrequency-selective repeaters 1189 a-b and hence experience differenttime-of-flights. In one configuration, one group of cells or channelsmay be established on path A 1187 a, while another group of cells orchannels may be established on path B 1187 b.

FIG. 12 is a diagram illustrating one example of uplink transmissiontiming with multiple cell groups 1293 a-b. In this example, it can beobserved that group A 1293 a includes a PCell 1295 and SCell1 1297 a.Furthermore, group B 1293 b includes a PSCell (e.g., SCell2) 1297 b,SCell3 1297 c and SCell4 1297 d. For group A 1293 a, the uplinktransmission timing 1299 a (for a PUSCH and/or SRS, for example) ofSCell1 1297 a may be the same as the uplink transmission timing 1299 afor a corresponding PCell 1295 in group A 1293 a. More specifically, theuplink transmission timing 1299 a for SCell1 uplink radio frame i 1285may be aligned (e.g., adjusted to approximately match) the uplinktransmission timing 1299 a of the PCell uplink radio frame i 1279. Asillustrated in FIG. 12, the transmission timing 1299 a of the PCelluplink radio frame i 1279 is based on the PCell downlink radio frame i1277. The timing for the SCell1 downlink radio frame i 1283 may vary.

For group B 1293 b, the uplink transmission timing 1299 b (for a PUSCHand/or SRS, for example) of SCell3 1297 c may be the same as the uplinktransmission timing 1299 b for the corresponding PSCell (SCell2) 1297 bin group B 1293 b. More specifically, the uplink transmission timing1299 b for SCell3 uplink radio frame i 1204 b may be aligned (e.g.,adjusted to approximately match) the uplink transmission timing 1299 bof the PSCell (SCell2) uplink radio frame i 1204 a. As illustrated inFIG. 12, the transmission timing 1299 b of the PSCell (SCell2) uplinkradio frame i 1204 a is based on the PSCell (SCell2) downlink radioframe i 1202 a. The timing for the SCell3 downlink radio frame i 1202 band the SCell4 downlink radio frame i 1202 c may vary. As illustrated inFIG. 12, a multiple serving cell concept may be that each serving cell1295, 1297 a-d has a respective downlink 1277, 1283, 1202 a-c and mayoptionally have a respective uplink 1279, 1285, 1204 a-b. Each servingdownlink carrier and uplink carrier may belong to one serving cell 1295,1297 a-d.

FIG. 13 is a diagram illustrating one example of uplink transmissiontiming adjustments 1318, 1320 in random access responses 1314, 1316. Inthis example, two groups 1393 a-b are illustrated. Group A 1393 aincludes a PCell downlink 1306, PCell uplink 1308, SCell1 downlink 1310a and SCell1 uplink 1312 a. The PCell downlink 1306 includes a randomaccess response 1314 that is used for a timing adjustment 1318 on thePCell uplink 1308 and SCell1 uplink 1312 a.

In this example, group B 1393 b includes a PSCell (SCell2) downlink 1310b, a PSCell (SCell2) uplink 1312 b, SCell3 downlink 1310 c, SCell3uplink 1312 c and SCell4 downlink 1310 d. The PSCell (SCell2) downlink1310 b includes a random access response 1316 that is used for a timingadjustment 1320 on the PSCell (SCell2) uplink 1312 b and SCell3 uplink1312 c.

A timing advance command in a random access response 1314, 1316 may betransmitted from an eNB 160 to a UE 102 in a PCell 1306 or in a PSCell1310 b after the UE 102 has sent a random access preamble in the PCell1306 or the PSCell 1310 b. Random access responses 1314, 1316 may bescheduled by a PDCCH including a random access radio network temporaryidentifier (RA-RNTI), which is an identifier used for scheduling a PDSCHincluding a random access response 1314, 1316.

The PCell uplink 1308 or SCell uplink 1312 a-c that a received randomaccess response 1314, 1316 corresponds to may be distinguished accordingto which serving or downlink cell 1306, 1310 a-d the random accessresponse 1314, 1316 is scheduled in. For example, a UE may determinewhich cell uplink 1308, 1312 a-c corresponds to a received random accessresponse 1314, 1316 by determining which serving cell downlink 1306,1310 b the random access response 1314, 1316 is scheduled in. A servingcell downlink 1306, 1310 b that the random access response 1314, 1316 isscheduled in may be determined by identifying a cell downlink 1306, 1310b that has a HARQ entity, a PDCCH or a PDSCH for a random accessresponse. The random access response 1314 scheduled in a PCell downlink1306 may be used for an uplink transmission timing adjustment 1318 for aPCell uplink 1308 and for any other SCell(s) 1312 a in the same group1393 a. The random access response 1316 scheduled in a PSCell downlink1310 b may be used for an uplink transmission timing adjustment 1320 fora PSCell uplink 1312 b and any other SCell(s) 1312 c in the same group1393 b.

FIG. 14 is a diagram illustrating one example of uplink transmissiontiming adjustments 1432, 1434, 1436, 1438, 1440 from timing advancecommand MAC control elements 1422, 1424, 1426, 1428, 1430. In thisexample, two groups 1493 a-b are illustrated. Group A 1493 a includes aPCell downlink 1406, PCell uplink 1408, SCell1 downlink 1410 a andSCell1 uplink 1412 a. The PCell downlink 1406 includes a timing advancecommand MAC control element 1422 that may be used for a timingadjustment 1432 on the PCell uplink 1408 and SCell1 uplink 1412 a.SCell1 downlink 1410 a includes a timing advance command MAC controlelement 1424 that may be used for a timing adjustment 1434 on the PCelluplink 1408 and SCell1 uplink 1412 a.

In this example, group B 1493 b includes a PSCell (SCell2) downlink 1410b, a PSCell (SCell2) uplink 1412 b, SCell3 downlink 1410 c, SCell3uplink 1412 c and SCell4 downlink 1410 d. The PSCell (SCell2) downlink1410 b includes a timing advance command MAC control element 1426 thatmay be used for a timing adjustment 1436 on the PSCell (SCell2) uplink1412 b and SCell3 uplink 1412 c. SCell3 downlink 1410 c includes atiming advance command MAC control element 1428 that may be used for atiming adjustment 1438 on the PSCell (SCell2) uplink 1412 b and SCell3uplink 1412 c. SCell4 downlink 1410 d includes a timing advance commandMAC control element 1430 that may be used for a timing adjustment 1440on the PSCell (SCell2) uplink 1412 b and SCell3 uplink 1412 c.

A timing advance command MAC control element 1422, 1424, 1426, 1428,1430 may be transmitted from an eNB 160 to the UE 102 at any time theeNB 160 wants to change the UE's 102 uplink transmission timing. Whetherthe received timing advance command MAC control element 1422, 1424,1426, 1428, 1430 is for the PCell 1408 or for a PSCell 1412 b may bedistinguished based on which serving cell downlink 1406, 1410 a-d thetiming advance command MAC control element is scheduled in. A servingcell downlink 1406, 1410 a-d that the timing advance command MAC controlelement 1422, 1424, 1426, 1428, 1430 is scheduled in may be determinedby identifying a cell downlink 1406, 1410 a-d that has a HARQ entity, aPDCCH or a PDSCH for a timing advance command MAC control element 1422,1424, 1426, 1428, 1430. A timing advance command MAC control element1422, 1424 scheduled in any serving cell downlink 1406, 1410 a in agroup 1493 a that includes the PCell downlink 1406 may be used for anuplink transmission timing adjustment 1432, 1434 for the PCell uplink1408 and for any SCell uplink(s) 1412 a in the same group 1493 a. Atiming advance command MAC control element 1426, 1428, 1430 scheduled inany serving cell downlink 1410 b-d in the group 1493 b that includes thePSCell downlink 1410 b may be used for an uplink transmission timingadjustment 1436, 1438, 1440 for the PSCell uplink 1412 b and for anyother SCell uplink(s) 1412 c in the same group 1493 b. In anotherconfiguration, a MAC header of the timing advance command MAC controlelement 1422, 1424, 1426, 1428, 1430 may indicate which group 1493 a-bthe command corresponds to.

FIG. 15 is a diagram illustrating one example of common space monitoringin multiple groups 1593 a-b. In this example, two groups 1593 a-b areillustrated. Group A 1593 a includes a PCell downlink 1506, PCell uplink1508, SCell1 downlink 1510 a and SCell1 uplink 1512 a. The PCelldownlink 1506 includes a common search space 1542. The PCell uplink 1508includes a random access channel (RACH) 1546 and/or a physical uplinkcontrol channel (PUCCH) 1548.

In this example, group B 1593 b includes a PSCell (SCell2) downlink 1510b, a PSCell (SCell2) uplink 1512 b, SCell3 downlink 1510 c, SCell3uplink 1512 c and SCell4 downlink 1510 d. The PSCell (SCell2) downlink1510 b includes a common search space 1544. The PSCell (SCell2) uplink1512 b includes a RACH 1550 and/or a PUCCH 1552.

Typically, there is only one common search space in a PCell and there isno common search space in an SCell. However, according to the systemsand methods disclosed herein, multiple common search spaces 1542, 1544may be used. A UE 102 may monitor a set of PDCCH candidates for controlinformation on one or more activated serving cell downlinks 1506, 1510a-d as configured by higher layer signaling. More than one serving cellmay be configured by RRC signaling and a serving cell may be activatedor deactivated by MAC signaling.

The set of PDCCH candidates to monitor may be defined in terms of searchspaces. There is a common search space 1542 on the PCell downlink 1506and a UE-specific search space on the PCell downlink 1506 and/or one ormore SCell downlinks 1510 a-d. Although the common search space 1542 maytypically be cell specific and only on the PCell downlink 1506, multiplecommon search spaces 1542, 1544 may be used and a common search space1544 may be defined on a PSCell 1510 b (e.g., SCell2) in accordance withthe systems and methods disclosed herein. A UE-specific search space maybe defined by a cell radio network temporary identifier or C-RNTI (e.g.,user equipment identifier (UEID)) and may be prepared for each servingcell downlink 1506, 1510 a-d.

Different kinds of information or data may be transmitted in a commonsearch space 1542, 1544. For example, a PDCCH to schedule systeminformation or paging information, random access related information ornormal UE data may be transmitted in the common search spaces 1542,1544. The physical layer of a UE 102 may be configured by higher layerswith a RNTI. The UE 102 may decode the PDCCH with a cyclic redundancycheck (CRC) scrambled by the RNTI. Downlink control information that isconveyed by PDCCH may have attached CRC. The CRC may be scrambled by theRNTI. For example, the CRC may be XORed with the RNTI. Some examples ofthe radio network temporary identifier (RNTI) include system informationRNTI (SI-RNTI), paging RNTI (P-RNTI), cell RNTI (C-RNTI), random accessRNTI (RA-RNTI), semi-persistent scheduling C-RNTI (SPS C-RNTI),temporary C-RNTI, transmit power control physical uplink control channelRNTI (TPC-PUCCH-RNTI) and transmit power control physical uplink sharedchannel RNTI (TPC-PUSCH-RNTI). In some cases, the UE 102 may monitor theRNTI (if it is configured to be monitored, for example). The RA-RNTI andthe temporary C-RNTI may be used for PDCCH random access-relatedscheduling information.

In order to have multiple time alignments, a UE 102 may need to performa random access procedure in a PSCell uplink 1512 b. Thus, a UE 102configured with an SCell 1512 b with a RACH 1550 may be required tomonitor a PDCCH in the common search space 1544 in the PSCell downlink1510 b in addition to the common search space 1542 in the PCell downlink1506. There may be no need to monitor a SI-RNTI, a P-RNTI and an SPSC-RNTI in the PSCell, since it may be sufficient to monitor them in thecommon search space 1542 in the PCell downlink 1506. Therefore, theC-RNTI, RA-RNTI, temporary C-RNTI, TPC-PUCCH-RNTI and TPC-PUSCH-RNTI maybe monitored by the UE 102 in the common search space 1544 in a PSCelldownlink 1510 b.

In accordance with the systems and methods disclosed herein, multiplePUCCHs 1548, 1552 may be used. For example, a PUCCH 1548 may beconfigured in a PCell uplink 1508 and a PUCCH 1552 may be configured ina PSCell uplink 1512 b (as allocated by an eNB 160, for example).

FIG. 16 illustrates various components that may be utilized in a UserEquipment (UE) 1602. The UE 1602 may be utilized as the UEs 102, 1002,1102 described above. The UE 1602 includes a processor 1654 thatcontrols operation of the UE 1602. The processor 1654 may also bereferred to as a CPU. Memory 1660, which may include read-only memory(ROM), random access memory (RAM), a combination of the two or any typeof device that may store information, provides instructions 1656 a anddata 1658 a to the processor 1654. A portion of the memory 1660 may alsoinclude non-volatile random access memory (NVRAM). Instructions 1656 band data 1658 b may also reside in the processor 1654. Instructions 1656b and/or data 1658 b loaded into the processor 1654 may also includeinstructions 1656 a and/or data 1658 a from memory 1660 that were loadedfor execution or processing by the processor 1654. The instructions 1656b may be executed by the processor 1654 to implement the systems andmethods disclosed herein.

The UE 1602 may also include a housing that contains one or moretransmitters 1658 and one or more receivers 1620 to allow transmissionand reception of data. The transmitter(s) 1658 and receiver(s) 1620 maybe combined into one or more transceivers 1618. One or more antennas1622 a-n are attached to the housing and electrically coupled to thetransceiver 1618.

The various components of the UE 1602 are coupled together by a bussystem 1666, which may include a power bus, a control signal bus, and astatus signal bus, in addition to a data bus. However, for the sake ofclarity, the various buses are illustrated in FIG. 16 as the bus system1666. The UE 1602 may also include a digital signal processor (DSP) 1662for use in processing signals. The UE 1602 may also include acommunications interface 1664 that provides user access to the functionsof the UE 1602. The UE 1602 illustrated in FIG. 16 is a functional blockdiagram rather than a listing of specific components.

FIG. 17 illustrates various components that may be utilized in anevolved Node B (eNB) 1760. The eNB 1760 may be utilized as one or moreof the eNBs 160, 1060, 1160 illustrated previously. The eNB 1760 mayinclude components that are similar to the components discussed above inrelation to the UE 1602, including a processor 1768, memory 1774 thatprovides instructions 1770 a and data 1772 a to the processor 1768,instructions 1770 b and data 1772 b that may reside in or be loaded intothe processor 1768, a housing that contains one or more transmitters1717 and one or more receivers 1778 (which may be combined into one ormore transceivers 1776), one or more antennas 1780 a-n electricallycoupled to the transceiver(s) 1776, a bus system 1782, a DSP 1776 foruse in processing signals, a communications interface 1778 and so forth.

The term “computer-readable medium” refers to any available medium thatcan be accessed by a computer or a processor. The term“computer-readable medium,” as used herein, may denote a computer-and/or processor-readable medium that is non-transitory and tangible. Byway of example, and not limitation, a computer-readable orprocessor-readable medium may comprise RAM, ROM, EEPROM, CD-ROM or otheroptical disk storage, magnetic disk storage or other magnetic storagedevices, or any other medium that can be used to carry or store desiredprogram code in the form of instructions or data structures and that canbe accessed by a computer or processor. Disk and disc, as used herein,includes compact disc (CD), laser disc, optical disc, digital versatiledisc (DVD), floppy disk and Blu-ray® disc where disks usually reproducedata magnetically, while discs reproduce data optically with lasers.

It should be noted that one or more of the methods described herein maybe implemented in and/or performed using hardware. For example, one ormore of the methods described herein may be implemented in and/orrealized using a chipset, an application-specific integrated circuit(ASIC), a large-scale integrated circuit (LSI) or integrated circuit,etc.

Each of the methods disclosed herein comprises one or more steps oractions for achieving the described method. The method steps and/oractions may be interchanged with one another and/or combined into asingle step without departing from the scope of the claims. In otherwords, unless a specific order of steps or actions is required forproper operation of the method that is being described, the order and/oruse of specific steps and/or actions may be modified without departingfrom the scope of the claims.

It is to be understood that the claims are not limited to the preciseconfiguration and components illustrated above. Various modifications,changes and variations may be made in the arrangement, operation anddetails of the systems, methods, and apparatus described herein withoutdeparting from the scope of the claims.

What is claimed is:
 1. A User Equipment (UE), comprising: a computerprocessor; a memory in electronic communication with the computerprocessor; instructions stored in the memory, the instructions beingexecutable by the computer processor to: receive, from a base station, aradio resource control, RRC, message including a configuration toconfigure multiple groups, each of which is constituted by one or moreserving cells; wherein a serving cell which is included in one group ofthe multiple groups is a primary cell (PCell), and a serving cell whichis included in another group of the multiple groups is a specific cell,decode a physical downlink control channel (PDCCH) with a cyclicredundancy check (CRC) scrambled by a first random access radio networktemporary identifier (RA-RNTI) in a common search space on the PCell;and decode a physical downlink control channel (PDCCH) with a cyclicredundancy check (CRC) scrambled by a second random access radio networktemporary identifier (RA-RNTI) in a common search space on the specificcell.
 2. A base station, comprising: a computer processor; a memory inelectronic communication with the computer processor; instructionsstored in the memory, the instructions being executable by the computerprocessor to: transmit, to a user equipment, a radio resource control,RRC, message including a configuration to configure multiple groups,each of which is constituted by one or more serving cells; wherein aserving cell which is included in one group of the multiple groups is aprimary cell (PCell), and a serving cell which is included in anothergroup of the multiple groups is a specific cell, encode a physicaldownlink control channel (PDCCH) with a cyclic redundancy check (CRC)scrambled by a random access radio network temporary identifier(RA-RNTI) in a common search space on the specific cell; and transmitthe PDCCH with the CRC scrambled by the RA-RNTI in the common searchspace on the specific cell.
 3. A method performed by a User Equipment(UE) comprising: receiving, from a base station, a radio resourcecontrol, RRC, message including a configuration to configure multiplegroups, each of which is constituted by one or more serving cells;wherein a serving cell which is included in one group of the multiplegroups is a primary cell (PCell), and a serving cell which is includedin another group of the multiple groups is a specific cell, decoding aphysical downlink control channel (PDCCH) with a cyclic redundancy check(CRC) scrambled by a first random access radio network temporaryidentifier (RA-RNTI) in a common search space on the PCell; and decodinga physical downlink control channel (PDCCH) with a cyclic redundancycheck (CRC) scrambled by a second random access radio network temporaryidentifier (RA-RNTI) in a common search space on the specific cell.
 4. Amethod performed by a base station comprising: transmitting, to a userequipment, a radio resource control, RRC, message including aconfiguration to configure multiple groups, each of which is constitutedby one or more serving cells; wherein a serving cell which is includedin one group of the multiple groups is a primary cell (PCell), and aserving cell which is included in another group of the multiple groupsis a specific cell, encoding a physical downlink control channel (PDCCH)with a cyclic redundancy check (CRC) scrambled by a random access radionetwork temporary identifier (RA-RNTI) in a common search space on thespecific cell; and transmitting the PDCCH with the CRC scrambled by theRA-RNTI in the common search space on the specific cell.